Make two naming changes:
1)
Standardize scheduler load-balancing function names on the
sched_balance_() prefix.
2)
Similar to find_busiest_queue(), the find_busiest_group() naming
has become a bit of a misnomer: the 'busiest' qualifier to this
function was historically correct but in the current code
in quite a few cases we will not pick the 'busiest' group - but the best
(possible) group we can balance from based on a complex set of
constraints.
So name it a bit more neutrally, similar to the 'src/dst' nomenclature
we are already using when moving tasks between runqueues, and also
use the sched_balance_ prefix: sched_balance_find_src_group().
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20240308111819.1101550-9-mingo@kernel.org
The find_busiest_queue() naming has two small quirks:
- Scheduler functions that deal with runqueues usually have a rq_ prefix
or _rq postfix, but this function has neither.
- Plus the 'busiest' qualifier to this function was historically
correct, but has become somewhat of a misnomer: in quite a few
cases we will not pick the busiest runqueue - but the best
(possible) runqueue we can balance tasks from. So name it a
bit more neutrally, similar to the 'src/dst' nomenclature
we are already using when moving tasks between runqueues.
To fix both quirks, and to standardize scheduler load-balancing
function names on the sched_balance_() prefix, rename the
function to sched_balance_find_src_rq().
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20240308111819.1101550-7-mingo@kernel.org
Standardize scheduler load-balancing function names on the
sched_balance_() prefix.
Also load_balance() has become somewhat of a misnomer: historically
it was the first and primary load-balancing function that was called,
but with the introduction of sched domains, it's become a lower
layer function that balances runqueues.
Rename it to sched_balance_rq() accordingly.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20240308111819.1101550-6-mingo@kernel.org
- Standardize on prefixing scheduler-internal functions defined
in <linux/sched.h> with sched_*() prefix. scheduler_tick() was
the only function using the scheduler_ prefix. Harmonize it.
- The other reason to rename it is the NOHZ scheduler tick
handling functions are already named sched_tick_*().
Make the 'git grep sched_tick' more meaningful.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20240308111819.1101550-3-mingo@kernel.org
run_rebalance_domains() is a misnomer, as it doesn't only
run rebalance_domains(), but since the introduction of the
NOHZ code it also runs nohz_idle_balance().
Rename it to sched_balance_softirq(), reflecting its more
generic purpose and that it's a softirq handler.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20240308111819.1101550-2-mingo@kernel.org
The first sentence of the comment explaining run_rebalance_domains()
is historic and not true anymore:
* run_rebalance_domains is triggered when needed from the scheduler tick.
... contradicted/modified by the second sentence:
* Also triggered for NOHZ idle balancing (with NOHZ_BALANCE_KICK set).
Avoid that kind of confusion straight away and explain from what
places sched_balance_softirq() is triggered.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20240308105901.1096078-9-mingo@kernel.org
Fix two typos:
- There's no such thing as 'nohz_balancing_kick', the
flag is named 'BALANCE' and is capitalized: NOHZ_BALANCE_KICK.
- Likewise there's no such thing as a 'pending nohz_balance_kick'
either, the NOHZ_BALANCE_KICK flag is all upper-case.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240308105901.1096078-8-mingo@kernel.org
So the scheduler has two such comment blocks, with '=' used as a double underline:
/*
* VRUNTIME
* ========
*
'========' also happens to be a Git conflict marker, throwing off a simple
search in an editor for this pattern.
Change them to '-------' type of underline instead - it looks just as good.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240308105901.1096078-7-mingo@kernel.org
We changed the order of definitions within 'enum cpu_idle_type',
which changed the order of [CPU_MAX_IDLE_TYPES] columns in
show_schedstat().
Suggested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: "Gautham R. Shenoy" <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20240308105901.1096078-5-mingo@kernel.org
The cpu_idle_type enum has the confusingly inverted property
that 'not idle' is 1, and 'idle' is '0'.
This resulted in a number of unnecessary complications in the code.
Reverse the order, remove the CPU_NOT_IDLE type, and convert
all code to a natural boolean form.
It's much more readable:
- enum cpu_idle_type idle = this_rq->idle_balance ?
- CPU_IDLE : CPU_NOT_IDLE;
-
+ enum cpu_idle_type idle = this_rq->idle_balance;
--------------------------------
- if (env->idle == CPU_NOT_IDLE || !busiest->sum_nr_running)
+ if (!env->idle || !busiest->sum_nr_running)
--------------------------------
And gets rid of the double negation in these usages:
- if (env->idle != CPU_NOT_IDLE && env->src_rq->nr_running <= 1)
+ if (env->idle && env->src_rq->nr_running <= 1)
Furthermore, this makes code much more obvious where there's
differentiation between CPU_IDLE and CPU_NEWLY_IDLE.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: "Gautham R. Shenoy" <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20240308105901.1096078-4-mingo@kernel.org
show_schedstat() output breaks and doesn't print all entries
if the ordering of the definitions in 'enum cpu_idle_type' is changed,
because show_schedstat() assumes that 'CPU_IDLE' is 0.
Fix it before we change the definition order & values.
[ mingo: Added changelog. ]
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240308105901.1096078-3-mingo@kernel.org
The 'balancing' spinlock added in:
08c183f31b ("[PATCH] sched: add option to serialize load balancing")
... is taken when the SD_SERIALIZE flag is set in a domain, but in reality it
is a glorified global atomic flag serializing the load-balancing of
those domains.
It doesn't have any explicit locking semantics per se: we just
spin_trylock() it.
Turn it into a ... global atomic flag. This makes it more
clear what is going on here, and reduces overhead and code
size a bit:
# kernel/sched/fair.o: [x86-64 defconfig]
text data bss dec hex filename
60730 2721 104 63555 f843 fair.o.before
60718 2721 104 63543 f837 fair.o.after
Also document the flag a bit.
No change in functionality intended.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20240308105901.1096078-2-mingo@kernel.org
- The biggest change is the rework of the percpu code,
to support the 'Named Address Spaces' GCC feature,
by Uros Bizjak:
- This allows C code to access GS and FS segment relative
memory via variables declared with such attributes,
which allows the compiler to better optimize those accesses
than the previous inline assembly code.
- The series also includes a number of micro-optimizations
for various percpu access methods, plus a number of
cleanups of %gs accesses in assembly code.
- These changes have been exposed to linux-next testing for
the last ~5 months, with no known regressions in this area.
- Fix/clean up __switch_to()'s broken but accidentally
working handling of FPU switching - which also generates
better code.
- Propagate more RIP-relative addressing in assembly code,
to generate slightly better code.
- Rework the CPU mitigations Kconfig space to be less idiosyncratic,
to make it easier for distros to follow & maintain these options.
- Rework the x86 idle code to cure RCU violations and
to clean up the logic.
- Clean up the vDSO Makefile logic.
- Misc cleanups and fixes.
[ Please note that there's a higher number of merge commits in
this branch (three) than is usual in x86 topic trees. This happened
due to the long testing lifecycle of the percpu changes that
involved 3 merge windows, which generated a longer history
and various interactions with other core x86 changes that we
felt better about to carry in a single branch. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core x86 updates from Ingo Molnar:
- The biggest change is the rework of the percpu code, to support the
'Named Address Spaces' GCC feature, by Uros Bizjak:
- This allows C code to access GS and FS segment relative memory
via variables declared with such attributes, which allows the
compiler to better optimize those accesses than the previous
inline assembly code.
- The series also includes a number of micro-optimizations for
various percpu access methods, plus a number of cleanups of %gs
accesses in assembly code.
- These changes have been exposed to linux-next testing for the
last ~5 months, with no known regressions in this area.
- Fix/clean up __switch_to()'s broken but accidentally working handling
of FPU switching - which also generates better code
- Propagate more RIP-relative addressing in assembly code, to generate
slightly better code
- Rework the CPU mitigations Kconfig space to be less idiosyncratic, to
make it easier for distros to follow & maintain these options
- Rework the x86 idle code to cure RCU violations and to clean up the
logic
- Clean up the vDSO Makefile logic
- Misc cleanups and fixes
* tag 'x86-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
x86/idle: Select idle routine only once
x86/idle: Let prefer_mwait_c1_over_halt() return bool
x86/idle: Cleanup idle_setup()
x86/idle: Clean up idle selection
x86/idle: Sanitize X86_BUG_AMD_E400 handling
sched/idle: Conditionally handle tick broadcast in default_idle_call()
x86: Increase brk randomness entropy for 64-bit systems
x86/vdso: Move vDSO to mmap region
x86/vdso/kbuild: Group non-standard build attributes and primary object file rules together
x86/vdso: Fix rethunk patching for vdso-image-{32,64}.o
x86/retpoline: Ensure default return thunk isn't used at runtime
x86/vdso: Use CONFIG_COMPAT_32 to specify vdso32
x86/vdso: Use $(addprefix ) instead of $(foreach )
x86/vdso: Simplify obj-y addition
x86/vdso: Consolidate targets and clean-files
x86/bugs: Rename CONFIG_RETHUNK => CONFIG_MITIGATION_RETHUNK
x86/bugs: Rename CONFIG_CPU_SRSO => CONFIG_MITIGATION_SRSO
x86/bugs: Rename CONFIG_CPU_IBRS_ENTRY => CONFIG_MITIGATION_IBRS_ENTRY
x86/bugs: Rename CONFIG_CPU_UNRET_ENTRY => CONFIG_MITIGATION_UNRET_ENTRY
x86/bugs: Rename CONFIG_SLS => CONFIG_MITIGATION_SLS
...
- Fix inconsistency in misfit task load-balancing
- Fix CPU isolation bugs in the task-wakeup logic
- Rework & unify the sched_use_asym_prio() and sched_asym_prefer() logic
- Clean up & simplify ->avg_* accesses
- Misc cleanups & fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Fix inconsistency in misfit task load-balancing
- Fix CPU isolation bugs in the task-wakeup logic
- Rework and unify the sched_use_asym_prio() and sched_asym_prefer()
logic
- Clean up and simplify ->avg_* accesses
- Misc cleanups and fixes
* tag 'sched-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/topology: Rename SD_SHARE_PKG_RESOURCES to SD_SHARE_LLC
sched/fair: Check the SD_ASYM_PACKING flag in sched_use_asym_prio()
sched/fair: Rework sched_use_asym_prio() and sched_asym_prefer()
sched/fair: Remove unused parameter from sched_asym()
sched/topology: Remove duplicate descriptions from TOPOLOGY_SD_FLAGS
sched/fair: Simplify the update_sd_pick_busiest() logic
sched/fair: Do strict inequality check for busiest misfit task group
sched/fair: Remove unnecessary goto in update_sd_lb_stats()
sched/fair: Take the scheduling domain into account in select_idle_core()
sched/fair: Take the scheduling domain into account in select_idle_smt()
sched/fair: Add READ_ONCE() and use existing helper function to access ->avg_irq
sched/fair: Use existing helper functions to access ->avg_rt and ->avg_dl
sched/core: Simplify code by removing duplicate #ifdefs
- The hierarchical timer pull model
When timer wheel timers are armed they are placed into the timer wheel
of a CPU which is likely to be busy at the time of expiry. This is done
to avoid wakeups on potentially idle CPUs.
This is wrong in several aspects:
1) The heuristics to select the target CPU are wrong by
definition as the chance to get the prediction right is close
to zero.
2) Due to #1 it is possible that timers are accumulated on a
single target CPU
3) The required computation in the enqueue path is just overhead for
dubious value especially under the consideration that the vast
majority of timer wheel timers are either canceled or rearmed
before they expire.
The timer pull model avoids the above by removing the target
computation on enqueue and queueing timers always on the CPU on which
they get armed.
This is achieved by having separate wheels for CPU pinned timers and
global timers which do not care about where they expire.
As long as a CPU is busy it handles both the pinned and the global
timers which are queued on the CPU local timer wheels.
When a CPU goes idle it evaluates its own timer wheels:
- If the first expiring timer is a pinned timer, then the global
timers can be ignored as the CPU will wake up before they expire.
- If the first expiring timer is a global timer, then the expiry time
is propagated into the timer pull hierarchy and the CPU makes sure
to wake up for the first pinned timer.
The timer pull hierarchy organizes CPUs in groups of eight at the
lowest level and at the next levels groups of eight groups up to the
point where no further aggregation of groups is required, i.e. the
number of levels is log8(NR_CPUS). The magic number of eight has been
established by experimention, but can be adjusted if needed.
In each group one busy CPU acts as the migrator. It's only one CPU to
avoid lock contention on remote timer wheels.
The migrator CPU checks in its own timer wheel handling whether there
are other CPUs in the group which have gone idle and have global timers
to expire. If there are global timers to expire, the migrator locks the
remote CPU timer wheel and handles the expiry.
Depending on the group level in the hierarchy this handling can require
to walk the hierarchy downwards to the CPU level.
Special care is taken when the last CPU goes idle. At this point the
CPU is the systemwide migrator at the top of the hierarchy and it
therefore cannot delegate to the hierarchy. It needs to arm its own
timer device to expire either at the first expiring timer in the
hierarchy or at the first CPU local timer, which ever expires first.
This completely removes the overhead from the enqueue path, which is
e.g. for networking a true hotpath and trades it for a slightly more
complex idle path.
This has been in development for a couple of years and the final series
has been extensively tested by various teams from silicon vendors and
ran through extensive CI.
There have been slight performance improvements observed on network
centric workloads and an Intel team confirmed that this allows them to
power down a die completely on a mult-die socket for the first time in
a mostly idle scenario.
There is only one outstanding ~1.5% regression on a specific overloaded
netperf test which is currently investigated, but the rest is either
positive or neutral performance wise and positive on the power
management side.
- Fixes for the timekeeping interpolation code for cross-timestamps:
cross-timestamps are used for PTP to get snapshots from hardware timers
and interpolated them back to clock MONOTONIC. The changes address a
few corner cases in the interpolation code which got the math and logic
wrong.
- Simplifcation of the clocksource watchdog retry logic to automatically
adjust to handle larger systems correctly instead of having more
incomprehensible command line parameters.
- Treewide consolidation of the VDSO data structures.
- The usual small improvements and cleanups all over the place.
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Merge tag 'timers-core-2024-03-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"A large set of updates and features for timers and timekeeping:
- The hierarchical timer pull model
When timer wheel timers are armed they are placed into the timer
wheel of a CPU which is likely to be busy at the time of expiry.
This is done to avoid wakeups on potentially idle CPUs.
This is wrong in several aspects:
1) The heuristics to select the target CPU are wrong by
definition as the chance to get the prediction right is
close to zero.
2) Due to #1 it is possible that timers are accumulated on
a single target CPU
3) The required computation in the enqueue path is just overhead
for dubious value especially under the consideration that the
vast majority of timer wheel timers are either canceled or
rearmed before they expire.
The timer pull model avoids the above by removing the target
computation on enqueue and queueing timers always on the CPU on
which they get armed.
This is achieved by having separate wheels for CPU pinned timers
and global timers which do not care about where they expire.
As long as a CPU is busy it handles both the pinned and the global
timers which are queued on the CPU local timer wheels.
When a CPU goes idle it evaluates its own timer wheels:
- If the first expiring timer is a pinned timer, then the global
timers can be ignored as the CPU will wake up before they
expire.
- If the first expiring timer is a global timer, then the expiry
time is propagated into the timer pull hierarchy and the CPU
makes sure to wake up for the first pinned timer.
The timer pull hierarchy organizes CPUs in groups of eight at the
lowest level and at the next levels groups of eight groups up to
the point where no further aggregation of groups is required, i.e.
the number of levels is log8(NR_CPUS). The magic number of eight
has been established by experimention, but can be adjusted if
needed.
In each group one busy CPU acts as the migrator. It's only one CPU
to avoid lock contention on remote timer wheels.
The migrator CPU checks in its own timer wheel handling whether
there are other CPUs in the group which have gone idle and have
global timers to expire. If there are global timers to expire, the
migrator locks the remote CPU timer wheel and handles the expiry.
Depending on the group level in the hierarchy this handling can
require to walk the hierarchy downwards to the CPU level.
Special care is taken when the last CPU goes idle. At this point
the CPU is the systemwide migrator at the top of the hierarchy and
it therefore cannot delegate to the hierarchy. It needs to arm its
own timer device to expire either at the first expiring timer in
the hierarchy or at the first CPU local timer, which ever expires
first.
This completely removes the overhead from the enqueue path, which
is e.g. for networking a true hotpath and trades it for a slightly
more complex idle path.
This has been in development for a couple of years and the final
series has been extensively tested by various teams from silicon
vendors and ran through extensive CI.
There have been slight performance improvements observed on network
centric workloads and an Intel team confirmed that this allows them
to power down a die completely on a mult-die socket for the first
time in a mostly idle scenario.
There is only one outstanding ~1.5% regression on a specific
overloaded netperf test which is currently investigated, but the
rest is either positive or neutral performance wise and positive on
the power management side.
- Fixes for the timekeeping interpolation code for cross-timestamps:
cross-timestamps are used for PTP to get snapshots from hardware
timers and interpolated them back to clock MONOTONIC. The changes
address a few corner cases in the interpolation code which got the
math and logic wrong.
- Simplifcation of the clocksource watchdog retry logic to
automatically adjust to handle larger systems correctly instead of
having more incomprehensible command line parameters.
- Treewide consolidation of the VDSO data structures.
- The usual small improvements and cleanups all over the place"
* tag 'timers-core-2024-03-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (62 commits)
timer/migration: Fix quick check reporting late expiry
tick/sched: Fix build failure for CONFIG_NO_HZ_COMMON=n
vdso/datapage: Quick fix - use asm/page-def.h for ARM64
timers: Assert no next dyntick timer look-up while CPU is offline
tick: Assume timekeeping is correctly handed over upon last offline idle call
tick: Shut down low-res tick from dying CPU
tick: Split nohz and highres features from nohz_mode
tick: Move individual bit features to debuggable mask accesses
tick: Move got_idle_tick away from common flags
tick: Assume the tick can't be stopped in NOHZ_MODE_INACTIVE mode
tick: Move broadcast cancellation up to CPUHP_AP_TICK_DYING
tick: Move tick cancellation up to CPUHP_AP_TICK_DYING
tick: Start centralizing tick related CPU hotplug operations
tick/sched: Don't clear ts::next_tick again in can_stop_idle_tick()
tick/sched: Rename tick_nohz_stop_sched_tick() to tick_nohz_full_stop_tick()
tick: Use IS_ENABLED() whenever possible
tick/sched: Remove useless oneshot ifdeffery
tick/nohz: Remove duplicate between lowres and highres handlers
tick/nohz: Remove duplicate between tick_nohz_switch_to_nohz() and tick_setup_sched_timer()
hrtimer: Select housekeeping CPU during migration
...
Memoryless nodes do not have any memory to migrate to, so, as an
optimization, stop trying it.
Link: https://lkml.kernel.org/r/20240219041920.1183-1-byungchul@sk.com
Link: https://lkml.kernel.org/r/20240216111502.79759-1-byungchul@sk.com
Fixes: c574bbe917 ("NUMA balancing: optimize page placement for memory tiering system")
Signed-off-by: Byungchul Park <byungchul@sk.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Benjamin Segall <bsegall@google.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The x86 architecture has an idle routine for AMD CPUs which are affected
by erratum 400. On the affected CPUs the local APIC timer stops in the
C1E halt state.
It therefore requires tick broadcasting. The invocation of
tick_broadcast_enter()/exit() from this function violates the RCU
constraints because it can end up in lockdep or tracing, which
rightfully triggers a warning.
tick_broadcast_enter()/exit() must be invoked before ct_cpuidle_enter()
and after ct_cpuidle_exit() in default_idle_call().
Add a static branch conditional invocation of tick_broadcast_enter()/exit()
into this function to allow X86 to replace the AMD specific idle code. It's
guarded by a config switch which will be selected by x86. Otherwise it's
a NOOP.
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240229142248.266708822@linutronix.de
SD_SHARE_PKG_RESOURCES is a bit of a misnomer: its naming suggests that
it's sharing all 'package resources' - while in reality it's specifically
for sharing the LLC only.
Rename it to SD_SHARE_LLC to reduce confusion.
[ mingo: Rewrote the confusing changelog as well. ]
Suggested-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Link: https://lore.kernel.org/r/20240210113924.1130448-5-alexs@kernel.org
sched_use_asym_prio() checks whether CPU priorities should be used. It
makes sense to check for the SD_ASYM_PACKING() inside the function.
Since both sched_asym() and sched_group_asym() use sched_use_asym_prio(),
remove the now superfluous checks for the flag in various places.
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240210113924.1130448-4-alexs@kernel.org
sched_use_asym_prio() and sched_asym_prefer() are used together in various
places. Consolidate them into a single function sched_asym().
The existing sched_asym() function is only used when collecting statistics
of a scheduling group. Rename it as sched_group_asym(), and remove the
obsolete function description.
This makes the code easier to read. No functional changes.
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240210113924.1130448-3-alexs@kernel.org
The 'sds' argument is not used in the sched_asym() function anymore, remove it.
Fixes: c9ca07886a ("sched/fair: Do not even the number of busy CPUs via asym_packing")
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240210113924.1130448-2-alexs@kernel.org
These flags are already documented in include/linux/sched/sd_flags.h.
Also, add missing SD_CLUSTER and keep the comment on SD_ASYM_PACKING
as it is a special case.
Suggested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240210113924.1130448-1-alexs@kernel.org
When comparing the current struct sched_group with the yet-busiest
domain in update_sd_pick_busiest(), if the two groups have the same
group type, we're currently doing a bit of unnecessary work for any
group >= group_misfit_task. We're comparing the two groups, and then
returning only if false (the group in question is not the busiest).
Otherwise, we break out, do an extra unnecessary conditional check that's
vacuously false for any group type > group_fully_busy, and then always
return true.
Let's just return directly in the switch statement instead. This doesn't
change the size of vmlinux with llvm 17 (not surprising given that all
of this is inlined in load_balance()), but it does shrink load_balance()
by 88 bytes on x86. Given that it also improves readability, this seems
worth doing.
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20240206043921.850302-4-void@manifault.com
In update_sd_pick_busiest(), when comparing two sched groups that are
both of type group_misfit_task, we currently consider the new group as
busier than the current busiest group even if the new group has the
same misfit task load as the current busiest group. We can avoid some
unnecessary writes if we instead only consider the newest group to be
the busiest if it has a higher load than the current busiest. This
matches the behavior of other group types where we compare load, such as
two groups that are both overloaded.
Let's update the group_misfit_task type comparison to also only update
the busiest group in the event of strict inequality.
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20240206043921.850302-3-void@manifault.com
In update_sd_lb_stats(), when we're iterating over the sched groups that
comprise a sched domain, we're skipping the call to
update_sd_pick_busiest() for the sched group that contains the local /
destination CPU. We use a goto to skip the call, but we could just as
easily check !local_group, as there's no other logic that we need to
skip with the goto. Let's remove the goto, and check for !local_group in
the if statement instead.
Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20240206043921.850302-2-void@manifault.com
When picking a CPU on task wakeup, select_idle_core() has to take
into account the scheduling domain where the function looks for the CPU.
This is because the "isolcpus" kernel command line option can remove CPUs
from the domain to isolate them from other SMT siblings.
This change replaces the set of CPUs allowed to run the task from
p->cpus_ptr by the intersection of p->cpus_ptr and sched_domain_span(sd)
which is stored in the 'cpus' argument provided by select_idle_cpu().
Fixes: 9fe1f127b9 ("sched/fair: Merge select_idle_core/cpu()")
Signed-off-by: Keisuke Nishimura <keisuke.nishimura@inria.fr>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240110131707.437301-2-keisuke.nishimura@inria.fr
When picking a CPU on task wakeup, select_idle_smt() has to take
into account the scheduling domain of @target. This is because the
"isolcpus" kernel command line option can remove CPUs from the domain to
isolate them from other SMT siblings.
This fix checks if the candidate CPU is in the target scheduling domain.
Commit:
df3cb4ea1f ("sched/fair: Fix wrong cpu selecting from isolated domain")
... originally introduced this fix by adding the check of the scheduling
domain in the loop.
However, commit:
3e6efe87cd ("sched/fair: Remove redundant check in select_idle_smt()")
... accidentally removed the check. Bring it back.
Fixes: 3e6efe87cd ("sched/fair: Remove redundant check in select_idle_smt()")
Signed-off-by: Keisuke Nishimura <keisuke.nishimura@inria.fr>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240110131707.437301-1-keisuke.nishimura@inria.fr
Use existing helper function cpu_util_irq() instead of open-coding
access to ->avg_irq.
During review it was noted that ->avg_irq could be updated by a
different CPU than the one which is trying to access it.
->avg_irq is updated with WRITE_ONCE(), use READ_ONCE to access it
in order to avoid any compiler optimizations.
Signed-off-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240101154624.100981-3-sshegde@linux.vnet.ibm.com
There are helper functions called cpu_util_dl() and cpu_util_rt() which give
the average utilization of DL and RT respectively. But there are a few
places in code where access to these variables is open-coded.
Instead use the helper function so that code becomes simpler and easier to
maintain later on.
No functional changes intended.
Signed-off-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240101154624.100981-2-sshegde@linux.vnet.ibm.com
The timekeeping duty is handed over from the outgoing CPU on stop
machine, then the oneshot tick is stopped right after. Therefore it's
guaranteed that the current CPU isn't the timekeeper upon its last call
to idle.
Besides, calling tick_nohz_idle_stop_tick() while the dying CPU goes
into idle suggests that the tick is going to be stopped while it is
actually stopped already from the appropriate CPU hotplug state.
Remove the confusing call and the obsolete case handling and convert it
to a sanity check that verifies the above assumption.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240225225508.11587-16-frederic@kernel.org
The new helper function is needed to help blk-mq check if it needs to
dispatch the softirq on another CPU to match the performance level the
IO requester is running at. This is important on HMP systems where not
all CPUs have the same compute capacity.
Signed-off-by: Qais Yousef <qyousef@layalina.io>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240223155749.2958009-2-qyousef@layalina.io
Signed-off-by: Jens Axboe <axboe@kernel.dk>
On some systems, sys_membarrier can be very expensive, causing overall
slowdowns for everything. So put a lock on the path in order to
serialize the accesses to prevent the ability for this to be called at
too high of a frequency and saturate the machine.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-and-tested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Fixes: 22e4ebb975 ("membarrier: Provide expedited private command")
Fixes: c5f58bd58f ("membarrier: Provide GLOBAL_EXPEDITED command")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's a few cases of nested #ifdefs in the scheduler code
that can be simplified:
#ifdef DEFINE_A
...code block...
#ifdef DEFINE_A <-- This is a duplicate.
...code block...
#endif
#else
#ifndef DEFINE_A <-- This is also duplicate.
...code block...
#endif
#endif
More details about the script and methods used to find these code
patterns can be found at:
https://lore.kernel.org/all/20240118080326.13137-1-sshegde@linux.ibm.com/
No change in functionality intended.
[ mingo: Clarified the changelog. ]
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240216061433.535522-1-sshegde@linux.ibm.com
RISC-V uses xRET instructions on return from interrupt and to go back
to user-space; the xRET instruction is not core serializing.
Use FENCE.I for providing core serialization as follows:
- by calling sync_core_before_usermode() on return from interrupt (cf.
ipi_sync_core()),
- via switch_mm() and sync_core_before_usermode() (respectively, for
uthread->uthread and kthread->uthread transitions) before returning
to user-space.
On RISC-V, the serialization in switch_mm() is activated by resetting
the icache_stale_mask of the mm at prepare_sync_core_cmd().
Suggested-by: Palmer Dabbelt <palmer@dabbelt.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/r/20240131144936.29190-5-parri.andrea@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Introduce an architecture function that architectures can use to set
up ("prepare") SYNC_CORE commands.
The function will be used by RISC-V to update its "deferred icache-
flush" data structures (icache_stale_mask).
Architectures defining prepare_sync_core_cmd() static inline need to
select ARCH_HAS_PREPARE_SYNC_CORE_CMD.
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/r/20240131144936.29190-4-parri.andrea@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
To gather the architecture requirements of the "private/global
expedited" membarrier commands. The file will be expanded to
integrate further information about the membarrier syscall (as
needed/desired in the future). While at it, amend some related
inline comments in the membarrier codebase.
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/r/20240131144936.29190-3-parri.andrea@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The membarrier system call requires a full memory barrier after storing
to rq->curr, before going back to user-space. The barrier is only
needed when switching between processes: the barrier is implied by
mmdrop() when switching from kernel to userspace, and it's not needed
when switching from userspace to kernel.
Rely on the feature/mechanism ARCH_HAS_MEMBARRIER_CALLBACKS and on the
primitive membarrier_arch_switch_mm(), already adopted by the PowerPC
architecture, to insert the required barrier.
Fixes: fab957c11e ("RISC-V: Atomic and Locking Code")
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/r/20240131144936.29190-2-parri.andrea@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Mark the task as having a cached timestamp when set assign it, so we
can efficiently check if it needs updating post being scheduled back in.
This covers both the actual schedule out case, which would've flushed
the plug, and the preemption case which doesn't touch the plugged
requests (for many reasons, one of them being then we'd need to have
preemption disabled around plug state manipulation).
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
where the CPU would remain at the lowest frequency, degrading
performance substantially.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-urgent-2024-01-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Ingo Molnar:
"Fix a cpufreq related performance regression on certain systems, where
the CPU would remain at the lowest frequency, degrading performance
substantially"
* tag 'sched-urgent-2024-01-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix frequency selection for non-invariant case
Linus reported a ~50% performance regression on single-threaded
workloads on his AMD Ryzen system, and bisected it to:
9c0b4bb7f6 ("sched/cpufreq: Rework schedutil governor performance estimation")
When frequency invariance is not enabled, get_capacity_ref_freq(policy)
is supposed to return the current frequency and the performance margin
applied by map_util_perf(), enabling the utilization to go above the
maximum compute capacity and to select a higher frequency than the current one.
After the changes in 9c0b4bb7f6, the performance margin was applied
earlier in the path to take into account utilization clampings and
we couldn't get a utilization higher than the maximum compute capacity,
and the CPU remained 'stuck' at lower frequencies.
To fix this, we must use a frequency above the current frequency to
get a chance to select a higher OPP when the current one becomes fully used.
Apply the same margin and return a frequency 25% higher than the current
one in order to switch to the next OPP before we fully use the CPU
at the current one.
[ mingo: Clarified the changelog. ]
Fixes: 9c0b4bb7f6 ("sched/cpufreq: Rework schedutil governor performance estimation")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Bisected-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Wyes Karny <wkarny@gmail.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Wyes Karny <wkarny@gmail.com>
Link: https://lore.kernel.org/r/20240114183600.135316-1-vincent.guittot@linaro.org
The goal is to get sched.h down to a type only header, so the main thing
happening in this patchset is splitting out various _types.h headers and
dependency fixups, as well as moving some things out of sched.h to
better locations.
This is prep work for the memory allocation profiling patchset which
adds new sched.h interdepencencies.
Testing - it's been in -next, and fixes from pretty much all
architectures have percolated in - nothing major.
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Merge tag 'header_cleanup-2024-01-10' of https://evilpiepirate.org/git/bcachefs
Pull header cleanups from Kent Overstreet:
"The goal is to get sched.h down to a type only header, so the main
thing happening in this patchset is splitting out various _types.h
headers and dependency fixups, as well as moving some things out of
sched.h to better locations.
This is prep work for the memory allocation profiling patchset which
adds new sched.h interdepencencies"
* tag 'header_cleanup-2024-01-10' of https://evilpiepirate.org/git/bcachefs: (51 commits)
Kill sched.h dependency on rcupdate.h
kill unnecessary thread_info.h include
Kill unnecessary kernel.h include
preempt.h: Kill dependency on list.h
rseq: Split out rseq.h from sched.h
LoongArch: signal.c: add header file to fix build error
restart_block: Trim includes
lockdep: move held_lock to lockdep_types.h
sem: Split out sem_types.h
uidgid: Split out uidgid_types.h
seccomp: Split out seccomp_types.h
refcount: Split out refcount_types.h
uapi/linux/resource.h: fix include
x86/signal: kill dependency on time.h
syscall_user_dispatch.h: split out *_types.h
mm_types_task.h: Trim dependencies
Split out irqflags_types.h
ipc: Kill bogus dependency on spinlock.h
shm: Slim down dependencies
workqueue: Split out workqueue_types.h
...
many places. The notable patch series are:
- nilfs2 folio conversion from Matthew Wilcox in "nilfs2: Folio
conversions for file paths".
- Additional nilfs2 folio conversion from Ryusuke Konishi in "nilfs2:
Folio conversions for directory paths".
- IA64 remnant removal in Heiko Carstens's "Remove unused code after
IA-64 removal".
- Arnd Bergmann has enabled the -Wmissing-prototypes warning everywhere
in "Treewide: enable -Wmissing-prototypes". This had some followup
fixes:
- Nathan Chancellor has cleaned up the hexagon build in the series
"hexagon: Fix up instances of -Wmissing-prototypes".
- Nathan also addressed some s390 warnings in "s390: A couple of
fixes for -Wmissing-prototypes".
- Arnd Bergmann addresses the same warnings for MIPS in his series
"mips: address -Wmissing-prototypes warnings".
- Baoquan He has made kexec_file operate in a top-down-fitting manner
similar to kexec_load in the series "kexec_file: Load kernel at top of
system RAM if required"
- Baoquan He has also added the self-explanatory "kexec_file: print out
debugging message if required".
- Some checkstack maintenance work from Tiezhu Yang in the series
"Modify some code about checkstack".
- Douglas Anderson has disentangled the watchdog code's logging when
multiple reports are occurring simultaneously. The series is "watchdog:
Better handling of concurrent lockups".
- Yuntao Wang has contributed some maintenance work on the crash code in
"crash: Some cleanups and fixes".
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Merge tag 'mm-nonmm-stable-2024-01-09-10-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
"Quite a lot of kexec work this time around. Many singleton patches in
many places. The notable patch series are:
- nilfs2 folio conversion from Matthew Wilcox in 'nilfs2: Folio
conversions for file paths'.
- Additional nilfs2 folio conversion from Ryusuke Konishi in 'nilfs2:
Folio conversions for directory paths'.
- IA64 remnant removal in Heiko Carstens's 'Remove unused code after
IA-64 removal'.
- Arnd Bergmann has enabled the -Wmissing-prototypes warning
everywhere in 'Treewide: enable -Wmissing-prototypes'. This had
some followup fixes:
- Nathan Chancellor has cleaned up the hexagon build in the series
'hexagon: Fix up instances of -Wmissing-prototypes'.
- Nathan also addressed some s390 warnings in 's390: A couple of
fixes for -Wmissing-prototypes'.
- Arnd Bergmann addresses the same warnings for MIPS in his series
'mips: address -Wmissing-prototypes warnings'.
- Baoquan He has made kexec_file operate in a top-down-fitting manner
similar to kexec_load in the series 'kexec_file: Load kernel at top
of system RAM if required'
- Baoquan He has also added the self-explanatory 'kexec_file: print
out debugging message if required'.
- Some checkstack maintenance work from Tiezhu Yang in the series
'Modify some code about checkstack'.
- Douglas Anderson has disentangled the watchdog code's logging when
multiple reports are occurring simultaneously. The series is
'watchdog: Better handling of concurrent lockups'.
- Yuntao Wang has contributed some maintenance work on the crash code
in 'crash: Some cleanups and fixes'"
* tag 'mm-nonmm-stable-2024-01-09-10-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (157 commits)
crash_core: fix and simplify the logic of crash_exclude_mem_range()
x86/crash: use SZ_1M macro instead of hardcoded value
x86/crash: remove the unused image parameter from prepare_elf_headers()
kdump: remove redundant DEFAULT_CRASH_KERNEL_LOW_SIZE
scripts/decode_stacktrace.sh: strip unexpected CR from lines
watchdog: if panicking and we dumped everything, don't re-enable dumping
watchdog/hardlockup: use printk_cpu_sync_get_irqsave() to serialize reporting
watchdog/softlockup: use printk_cpu_sync_get_irqsave() to serialize reporting
watchdog/hardlockup: adopt softlockup logic avoiding double-dumps
kexec_core: fix the assignment to kimage->control_page
x86/kexec: fix incorrect end address passed to kernel_ident_mapping_init()
lib/trace_readwrite.c:: replace asm-generic/io with linux/io
nilfs2: cpfile: fix some kernel-doc warnings
stacktrace: fix kernel-doc typo
scripts/checkstack.pl: fix no space expression between sp and offset
x86/kexec: fix incorrect argument passed to kexec_dprintk()
x86/kexec: use pr_err() instead of kexec_dprintk() when an error occurs
nilfs2: add missing set_freezable() for freezable kthread
kernel: relay: remove relay_file_splice_read dead code, doesn't work
docs: submit-checklist: remove all of "make namespacecheck"
...
When a CPU is taken offline, the contribution of its cfs_rqs to task_groups'
load may remain and will negatively impact the calculation of the share of
the online CPUs.
To fix this bug, clear the contribution of an offlining CPU to task groups'
load and skip its contribution while it is inactive.
Here's the reproducer of the anomaly, by Imran Khan:
"So far I have encountered only one rather lengthy way of reproducing this issue,
which is as follows:
1. Take a KVM guest (booted with 4 CPUs and can be scaled up to 124 CPUs) and
create 2 custom cgroups: /sys/fs/cgroup/cpu/test_group_1 and /sys/fs/cgroup/
cpu/test_group_2
2. Assign a CPU intensive workload to each of these cgroups and start the
workload.
For my tests I am using following app:
int main(int argc, char *argv[])
{
unsigned long count, i, val;
if (argc != 2) {
printf("usage: ./a.out <number of random nums to generate> \n");
return 0;
}
count = strtoul(argv[1], NULL, 10);
printf("Generating %lu random numbers \n", count);
for (i = 0; i < count; i++) {
val = rand();
val = val % 2;
//usleep(1);
}
printf("Generated %lu random numbers \n", count);
return 0;
}
Also since the system is booted with 4 CPUs, in order to completely load the
system I am also launching 4 instances of same test app under:
/sys/fs/cgroup/cpu/
3. We can see that both of the cgroups get similar CPU time:
# systemd-cgtop --depth 1
Path Tasks %CPU Memory Input/s Output/s
/ 659 - 5.5G - -
/system.slice - - 5.7G - -
/test_group_1 4 - - - -
/test_group_2 3 - - - -
/user.slice 31 - 56.5M - -
Path Tasks %CPU Memory Input/s Output/s
/ 659 394.6 5.5G - -
/test_group_2 3 65.7 - - -
/user.slice 29 55.1 48.0M - -
/test_group_1 4 47.3 - - -
/system.slice - 2.2 5.7G - -
Path Tasks %CPU Memory Input/s Output/s
/ 659 394.8 5.5G - -
/test_group_1 4 62.9 - - -
/user.slice 28 44.9 54.2M - -
/test_group_2 3 44.7 - - -
/system.slice - 0.9 5.7G - -
Path Tasks %CPU Memory Input/s Output/s
/ 659 394.4 5.5G - -
/test_group_2 3 58.8 - - -
/test_group_1 4 51.9 - - -
/user.slice 30 39.3 59.6M - -
/system.slice - 1.9 5.7G - -
Path Tasks %CPU Memory Input/s Output/s
/ 659 394.7 5.5G - -
/test_group_1 4 60.9 - - -
/test_group_2 3 57.9 - - -
/user.slice 28 43.5 36.9M - -
/system.slice - 3.0 5.7G - -
Path Tasks %CPU Memory Input/s Output/s
/ 659 395.0 5.5G - -
/test_group_1 4 66.8 - - -
/test_group_2 3 56.3 - - -
/user.slice 29 43.1 51.8M - -
/system.slice - 0.7 5.7G - -
4. Now move systemd-udevd to one of these test groups, say test_group_1, and
perform scale up to 124 CPUs followed by scale down back to 4 CPUs from the
host side.
5. Run the same workload i.e 4 instances of CPU hogger under /sys/fs/cgroup/cpu
and one instance of CPU hogger each in /sys/fs/cgroup/cpu/test_group_1 and
/sys/fs/cgroup/test_group_2.
It can be seen that test_group_1 (the one where systemd-udevd was moved) is getting
much less CPU time than the test_group_2, even though at this point of time both of
these groups have only CPU hogger running:
# systemd-cgtop --depth 1
Path Tasks %CPU Memory Input/s Output/s
/ 1219 - 5.4G - -
/system.slice - - 5.6G - -
/test_group_1 4 - - - -
/test_group_2 3 - - - -
/user.slice 26 - 91.3M - -
Path Tasks %CPU Memory Input/s Output/s
/ 1221 394.3 5.4G - -
/test_group_2 3 82.7 - - -
/test_group_1 4 14.3 - - -
/system.slice - 0.8 5.6G - -
/user.slice 26 0.4 91.2M - -
Path Tasks %CPU Memory Input/s Output/s
/ 1221 394.6 5.4G - -
/test_group_2 3 67.4 - - -
/system.slice - 24.6 5.6G - -
/test_group_1 4 12.5 - - -
/user.slice 26 0.4 91.2M - -
Path Tasks %CPU Memory Input/s Output/s
/ 1221 395.2 5.4G - -
/test_group_2 3 60.9 - - -
/system.slice - 27.9 5.6G - -
/test_group_1 4 12.2 - - -
/user.slice 26 0.4 91.2M - -
Path Tasks %CPU Memory Input/s Output/s
/ 1221 395.2 5.4G - -
/test_group_2 3 69.4 - - -
/test_group_1 4 13.9 - - -
/user.slice 28 1.6 92.0M - -
/system.slice - 1.0 5.6G - -
Path Tasks %CPU Memory Input/s Output/s
/ 1221 395.6 5.4G - -
/test_group_2 3 59.3 - - -
/test_group_1 4 14.1 - - -
/user.slice 28 1.3 92.2M - -
/system.slice - 0.7 5.6G - -
Path Tasks %CPU Memory Input/s Output/s
/ 1221 395.5 5.4G - -
/test_group_2 3 67.2 - - -
/test_group_1 4 11.5 - - -
/user.slice 28 1.3 92.5M - -
/system.slice - 0.6 5.6G - -
Path Tasks %CPU Memory Input/s Output/s
/ 1221 395.1 5.4G - -
/test_group_2 3 76.8 - - -
/test_group_1 4 12.9 - - -
/user.slice 28 1.3 92.8M - -
/system.slice - 1.2 5.6G - -
From sched_debug data it can be seen that in bad case the load.weight of per-CPU
sched entities corresponding to test_group_1 has reduced significantly and
also load_avg of test_group_1 remains much higher than that of test_group_2,
even though systemd-udevd stopped running long time back and at this point of
time both cgroups just have the CPU hogger app as running entity."
[ mingo: Added details from the original discussion, plus minor edits to the patch. ]
Reported-by: Imran Khan <imran.f.khan@oracle.com>
Tested-by: Imran Khan <imran.f.khan@oracle.com>
Tested-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Imran Khan <imran.f.khan@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lore.kernel.org/r/20231223111545.62135-1-vincent.guittot@linaro.org
We're trying to get sched.h down to more or less just types only, not
code - rseq can live in its own header.
This helps us kill the dependency on preempt.h in sched.h.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Running N CPU-bound tasks on an N CPUs platform:
- with asymmetric CPU capacity
- not being a DynamIq system (i.e. having a PKG level sched domain
without the SD_SHARE_PKG_RESOURCES flag set)
.. might result in a task placement where two tasks run on a big CPU
and none on a little CPU. This placement could be more optimal by
using all CPUs.
Testing platform:
Juno-r2:
- 2 big CPUs (1-2), maximum capacity of 1024
- 4 little CPUs (0,3-5), maximum capacity of 383
Testing workload ([1]):
Spawn 6 CPU-bound tasks. During the first 100ms (step 1), each tasks
is affine to a CPU, except for:
- one little CPU which is left idle.
- one big CPU which has 2 tasks affine.
After the 100ms (step 2), remove the cpumask affinity.
Behavior before the patch:
During step 2, the load balancer running from the idle CPU tags sched
domains as:
- little CPUs: 'group_has_spare'. Cf. group_has_capacity() and
group_is_overloaded(), 3 CPU-bound tasks run on a 4 CPUs
sched-domain, and the idle CPU provides enough spare capacity
regarding the imbalance_pct
- big CPUs: 'group_overloaded'. Indeed, 3 tasks run on a 2 CPUs
sched-domain, so the following path is used:
group_is_overloaded()
\-if (sgs->sum_nr_running <= sgs->group_weight) return true;
The following path which would change the migration type to
'migrate_task' is not taken:
calculate_imbalance()
\-if (env->idle != CPU_NOT_IDLE && env->imbalance == 0)
as the local group has some spare capacity, so the imbalance
is not 0.
The migration type requested is 'migrate_util' and the busiest
runqueue is the big CPU's runqueue having 2 tasks (each having a
utilization of 512). The idle little CPU cannot pull one of these
task as its capacity is too small for the task. The following path
is used:
detach_tasks()
\-case migrate_util:
\-if (util > env->imbalance) goto next;
After the patch:
As the number of failed balancing attempts grows (with
'nr_balance_failed'), progressively make it easier to migrate
a big task to the idling little CPU. A similar mechanism is
used for the 'migrate_load' migration type.
Improvement:
Running the testing workload [1] with the step 2 representing
a ~10s load for a big CPU:
Before patch: ~19.3s
After patch: ~18s (-6.7%)
Similar issue reported at:
https://lore.kernel.org/lkml/20230716014125.139577-1-qyousef@layalina.io/
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Qais Yousef <qyousef@layalina.io>
Link: https://lore.kernel.org/r/20231206090043.634697-1-pierre.gondois@arm.com
With UTIL_EST_FASTUP now being permanent, we can take advantage of the
fact that the ewma jumps directly to a higher utilization at dequeue to
simplify util_est and remove the enqueued field.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Hongyan Xia <hongyan.xia2@arm.com>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/20231201161652.1241695-3-vincent.guittot@linaro.org
sched_feat(UTIL_EST_FASTUP) has been added to easily disable the feature
in order to check for possibly related regressions. After 3 years, it has
never been used and no regression has been reported. Let's remove it
and make fast increase a permanent behavior.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Hongyan Xia <hongyan.xia2@arm.com>
Reviewed-by: Tang Yizhou <yizhou.tang@shopee.com>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn> [for the Chinese translation]
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/20231201161652.1241695-2-vincent.guittot@linaro.org
cpuinfo.max_freq can change at runtime because of boost as an example. This
implies that the value could be different than the one that has been
used when computing the capacity of a CPU.
The new arch_scale_freq_ref() returns a fixed and coherent reference
frequency that can be used when computing a frequency based on utilization.
Use this arch_scale_freq_ref() when available and fallback to
policy otherwise.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/20231211104855.558096-4-vincent.guittot@linaro.org
These four functions have a normal definition for CONFIG_FAIR_GROUP_SCHED,
and empty one that is only referenced when FAIR_GROUP_SCHED is disabled
but CGROUP_SCHED is still enabled. If both are turned off, the functions
are still defined but the misisng prototype causes a W=1 warning:
kernel/sched/fair.c:12544:6: error: no previous prototype for 'free_fair_sched_group'
kernel/sched/fair.c:12546:5: error: no previous prototype for 'alloc_fair_sched_group'
kernel/sched/fair.c:12553:6: error: no previous prototype for 'online_fair_sched_group'
kernel/sched/fair.c:12555:6: error: no previous prototype for 'unregister_fair_sched_group'
Move the alternatives into the header as static inline functions with the
correct combination of #ifdef checks to avoid the warning without adding
even more complexity.
[A different patch with the same description got applied by accident
and was later reverted, but the original patch is still missing]
Link: https://lkml.kernel.org/r/20231123110506.707903-4-arnd@kernel.org
Fixes: 7aa55f2a59 ("sched/fair: Move unused stub functions to header")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Tudor Ambarus <tudor.ambarus@linaro.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Since reweight_entity() may have chance to change the weight of
cfs_rq->curr entity, we should also update_min_vruntime() if
this is the case
Fixes: eab03c23c2 ("sched/eevdf: Fix vruntime adjustment on reweight")
Signed-off-by: Yiwei Lin <s921975628@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Abel Wu <wuyun.abel@bytedance.com>
Link: https://lore.kernel.org/r/20231117080106.12890-1-s921975628@gmail.com
Use the max value that has already been computed inside sugov_get_util()
to cap the iowait boost and remove dependency with uclamp_rq_util_with()
which is not used anymore.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20231122133904.446032-3-vincent.guittot@linaro.org
The current method to take into account uclamp hints when estimating the
target frequency can end in a situation where the selected target
frequency is finally higher than uclamp hints, whereas there are no real
needs. Such cases mainly happen because we are currently mixing the
traditional scheduler utilization signal with the uclamp performance
hints. By adding these 2 metrics, we loose an important information when
it comes to select the target frequency, and we have to make some
assumptions which can't fit all cases.
Rework the interface between the scheduler and schedutil governor in order
to propagate all information down to the cpufreq governor.
effective_cpu_util() interface changes and now returns the actual
utilization of the CPU with 2 optional inputs:
- The minimum performance for this CPU; typically the capacity to handle
the deadline task and the interrupt pressure. But also uclamp_min
request when available.
- The maximum targeting performance for this CPU which reflects the
maximum level that we would like to not exceed. By default it will be
the CPU capacity but can be reduced because of some performance hints
set with uclamp. The value can be lower than actual utilization and/or
min performance level.
A new sugov_effective_cpu_perf() interface is also available to compute
the final performance level that is targeted for the CPU, after applying
some cpufreq headroom and taking into account all inputs.
With these 2 functions, schedutil is now able to decide when it must go
above uclamp hints. It now also has a generic way to get the min
performance level.
The dependency between energy model and cpufreq governor and its headroom
policy doesn't exist anymore.
eenv_pd_max_util() asks schedutil for the targeted performance after
applying the impact of the waking task.
[ mingo: Refined the changelog & C comments. ]
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20231122133904.446032-2-vincent.guittot@linaro.org
Lukasz Luba reported that a thread's util_est can significantly decrease as
a result of sharing the CPU with other threads.
The use case can be easily reproduced with a periodic task TA that runs 1ms
and sleeps 100us. When the task is alone on the CPU, its max utilization and
its util_est is around 888. If another similar task starts to run on the
same CPU, TA will have to share the CPU runtime and its maximum utilization
will decrease around half the CPU capacity (512) then TA's util_est will
follow this new maximum trend which is only the result of sharing the CPU
with others tasks.
Such situation can be detected with runnable_avg wich is close or
equal to util_avg when TA is alone, but increases above util_avg when TA
shares the CPU with other threads and wait on the runqueue.
[ We prefer an util_est that overestimate rather than under estimate
because in 1st case we will not provide enough performance to the
task which will remain under-provisioned, whereas in the other case we
will create some idle time which will enable to reduce contention and
as a result reduces the util_est so the overestimate will be transient
whereas the underestimate will remain. ]
[ mingo: Refined the changelog, added comments from the LKML discussion. ]
Reported-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/lkml/CAKfTPtDd-HhF-YiNTtL9i5k0PfJbF819Yxu4YquzfXgwi7voyw@mail.gmail.com/#t
Link: https://lore.kernel.org/r/20231122140119.472110-1-vincent.guittot@linaro.org
Cc: Hongyan Xia <hongyan.xia2@arm.com>
Trying to avoid that didn't bring much value after testing, add comment
about this.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lkml.kernel.org/r/20231114193840.4041-3-frederic@kernel.org
Add missing explanation concerning IRQs re-enablement constraints in
the cpuidle path against timers.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lkml.kernel.org/r/20231114193840.4041-2-frederic@kernel.org
Low priority tasks (e.g., SCHED_OTHER) can suffer starvation if tasks
with higher priority (e.g., SCHED_FIFO) monopolize CPU(s).
RT Throttling has been introduced a while ago as a (mostly debug)
countermeasure one can utilize to reserve some CPU time for low priority
tasks (usually background type of work, e.g. workqueues, timers, etc.).
It however has its own problems (see documentation) and the undesired
effect of unconditionally throttling FIFO tasks even when no lower
priority activity needs to run (there are mechanisms to fix this issue
as well, but, again, with their own problems).
Introduce deadline servers to service low priority tasks needs under
starvation conditions. Deadline servers are built extending SCHED_DEADLINE
implementation to allow 2-level scheduling (a sched_deadline entity
becomes a container for lower priority scheduling entities).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/4968601859d920335cf85822eb573a5f179f04b8.1699095159.git.bristot@kernel.org
In preparation of introducing !task sched_dl_entity; move the
bandwidth accounting into {en.de}queue_dl_entity().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lkml.kernel.org/r/a86dccbbe44e021b8771627e1dae01a69b73466d.1699095159.git.bristot@kernel.org
Create a single function that initializes a sched_dl_entity.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lkml.kernel.org/r/51acc695eecf0a1a2f78f9a044e11ffd9b316bcf.1699095159.git.bristot@kernel.org
Now that trace_sched_stat_runtime() no longer takes a vruntime
argument, the task specific bits are identical between
update_curr_common() and update_curr().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tracing the runtime delta makes sense, observer can sum over time.
Tracing the absolute vruntime makes less sense, inconsistent:
absolute-vs-delta, but also vruntime delta can be computed from
runtime delta.
Removing the vruntime thing also makes the two tracepoint sites
identical, allowing to unify the code in a later patch.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
All classes use sched_entity::exec_start to track runtime and have
copies of the exact same code around to compute runtime.
Collapse all that.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/54d148a144f26d9559698c4dd82d8859038a7380.1699095159.git.bristot@kernel.org
Since the RB-tree is now sorted by deadline, let's first try the
leftmost entity which has the earliest virtual deadline. I've done
some benchmarks to see its effectiveness.
All the benchmarks are done inside a normal cpu cgroup in a clean
environment with cpu turbo disabled, on a dual-CPU Intel Xeon(R)
Platinum 8260 with 2 NUMA nodes each of which has 24C/48T.
hackbench: process/thread + pipe/socket + 1/2/4/8 groups
netperf: TCP/UDP + STREAM/RR + 24/48/72/96/192 threads
tbench: loopback 24/48/72/96/192 threads
schbench: 1/2/4/8 mthreads
direct: cfs_rq has only one entity
parity: RUN_TO_PARITY
fast: O(1) fastpath
slow: heap search
(%) direct parity fast slow
hackbench 92.95 2.02 4.91 0.12
netperf 68.08 6.60 24.18 1.14
tbench 67.55 11.22 20.61 0.62
schbench 69.91 2.65 25.73 1.71
The above results indicate that this fastpath really makes task
selection more efficient.
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231115033647.80785-4-wuyun.abel@bytedance.com
Sort the task timeline by virtual deadline and keep the min_vruntime
in the augmented tree, so we can avoid doubling the worst case cost
and make full use of the cached leftmost node to enable O(1) fastpath
picking in next patch.
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231115033647.80785-3-wuyun.abel@bytedance.com
Since commit fc137c0dda ("sched/numa: enhance vma scanning logic")
NUMA Balancing allows updating PTEs to trap NUMA hinting faults if the
task had previously accessed VMA. However unconditional scan of VMAs are
allowed during initial phase of VMA creation until process's
mm numa_scan_seq reaches 2 even though current task had not accessed VMA.
Rationale:
- Without initial scan subsequent PTE update may never happen.
- Give fair opportunity to all the VMAs to be scanned and subsequently
understand the access pattern of all the VMAs.
But it has a corner case where, if a VMA is created after some time,
process's mm numa_scan_seq could be already greater than 2.
For e.g., values of mm numa_scan_seq when VMAs are created by running
mmtest autonuma benchmark briefly looks like:
start_seq=0 : 459
start_seq=2 : 138
start_seq=3 : 144
start_seq=4 : 8
start_seq=8 : 1
start_seq=9 : 1
This results in no unconditional PTE updates for those VMAs created after
some time.
Fix:
- Note down the initial value of mm numa_scan_seq in per VMA start_seq.
- Allow unconditional scan till start_seq + 2.
Result:
SUT: AMD EPYC Milan with 2 NUMA nodes 256 cpus.
base kernel: upstream 6.6-rc6 with Mels patches [1] applied.
kernbench
========== base patched %gain
Amean elsp-128 165.09 ( 0.00%) 164.78 * 0.19%*
Duration User 41404.28 41375.08
Duration System 9862.22 9768.48
Duration Elapsed 519.87 518.72
Ops NUMA PTE updates 1041416.00 831536.00
Ops NUMA hint faults 263296.00 220966.00
Ops NUMA pages migrated 258021.00 212769.00
Ops AutoNUMA cost 1328.67 1114.69
autonumabench
NUMA01_THREADLOCAL
==================
Amean elsp-NUMA01_THREADLOCAL 81.79 (0.00%) 67.74 * 17.18%*
Duration User 54832.73 47379.67
Duration System 75.00 185.75
Duration Elapsed 576.72 476.09
Ops NUMA PTE updates 394429.00 11121044.00
Ops NUMA hint faults 1001.00 8906404.00
Ops NUMA pages migrated 288.00 2998694.00
Ops AutoNUMA cost 7.77 44666.84
Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/2ea7cbce80ac7c62e90cbfb9653a7972f902439f.1697816692.git.raghavendra.kt@amd.com
should_we_balance is called for the decision to do load-balancing.
When sched ticks invoke this function, only one CPU should return
true. However, in the current code, two CPUs can return true. The
following situation, where b means busy and i means idle, is an
example, because CPU 0 and CPU 2 return true.
[0, 1] [2, 3]
b b i b
This fix checks if there exists an idle CPU with busy sibling(s)
after looking for a CPU on an idle core. If some idle CPUs with busy
siblings are found, just the first one should do load-balancing.
Fixes: b1bfeab9b0 ("sched/fair: Consider the idle state of the whole core for load balance")
Signed-off-by: Keisuke Nishimura <keisuke.nishimura@inria.fr>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20231031133821.1570861-1-keisuke.nishimura@inria.fr
vruntime of the (on_rq && !0-lag) entity needs to be adjusted when
it gets re-weighted, and the calculations can be simplified based
on the fact that re-weight won't change the w-average of all the
entities. Please check the proofs in comments.
But adjusting vruntime can also cause position change in RB-tree
hence require re-queue to fix up which might be costly. This might
be avoided by deferring adjustment to the time the entity actually
leaves tree (dequeue/pick), but that will negatively affect task
selection and probably not good enough either.
Fixes: 147f3efaa2 ("sched/fair: Implement an EEVDF-like scheduling policy")
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231107090510.71322-2-wuyun.abel@bytedance.com
there's little I can say which isn't in the individual changelogs.
The lengthier patch series are
- "kdump: use generic functions to simplify crashkernel reservation in
arch", from Baoquan He. This is mainly cleanups and consolidation of
the "crashkernel=" kernel parameter handling.
- After much discussion, David Laight's "minmax: Relax type checks in
min() and max()" is here. Hopefully reduces some typecasting and the
use of min_t() and max_t().
- A group of patches from Oleg Nesterov which clean up and slightly fix
our handling of reads from /proc/PID/task/... and which remove
task_struct.therad_group.
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Merge tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
"As usual, lots of singleton and doubleton patches all over the tree
and there's little I can say which isn't in the individual changelogs.
The lengthier patch series are
- 'kdump: use generic functions to simplify crashkernel reservation
in arch', from Baoquan He. This is mainly cleanups and
consolidation of the 'crashkernel=' kernel parameter handling
- After much discussion, David Laight's 'minmax: Relax type checks in
min() and max()' is here. Hopefully reduces some typecasting and
the use of min_t() and max_t()
- A group of patches from Oleg Nesterov which clean up and slightly
fix our handling of reads from /proc/PID/task/... and which remove
task_struct.thread_group"
* tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (64 commits)
scripts/gdb/vmalloc: disable on no-MMU
scripts/gdb: fix usage of MOD_TEXT not defined when CONFIG_MODULES=n
.mailmap: add address mapping for Tomeu Vizoso
mailmap: update email address for Claudiu Beznea
tools/testing/selftests/mm/run_vmtests.sh: lower the ptrace permissions
.mailmap: map Benjamin Poirier's address
scripts/gdb: add lx_current support for riscv
ocfs2: fix a spelling typo in comment
proc: test ProtectionKey in proc-empty-vm test
proc: fix proc-empty-vm test with vsyscall
fs/proc/base.c: remove unneeded semicolon
do_io_accounting: use sig->stats_lock
do_io_accounting: use __for_each_thread()
ocfs2: replace BUG_ON() at ocfs2_num_free_extents() with ocfs2_error()
ocfs2: fix a typo in a comment
scripts/show_delta: add __main__ judgement before main code
treewide: mark stuff as __ro_after_init
fs: ocfs2: check status values
proc: test /proc/${pid}/statm
compiler.h: move __is_constexpr() to compiler.h
...
included in this merge do the following:
- Kemeng Shi has contributed some compation maintenance work in the
series "Fixes and cleanups to compaction".
- Joel Fernandes has a patchset ("Optimize mremap during mutual
alignment within PMD") which fixes an obscure issue with mremap()'s
pagetable handling during a subsequent exec(), based upon an
implementation which Linus suggested.
- More DAMON/DAMOS maintenance and feature work from SeongJae Park i the
following patch series:
mm/damon: misc fixups for documents, comments and its tracepoint
mm/damon: add a tracepoint for damos apply target regions
mm/damon: provide pseudo-moving sum based access rate
mm/damon: implement DAMOS apply intervals
mm/damon/core-test: Fix memory leaks in core-test
mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval
- In the series "Do not try to access unaccepted memory" Adrian Hunter
provides some fixups for the recently-added "unaccepted memory' feature.
To increase the feature's checking coverage. "Plug a few gaps where
RAM is exposed without checking if it is unaccepted memory".
- In the series "cleanups for lockless slab shrink" Qi Zheng has done
some maintenance work which is preparation for the lockless slab
shrinking code.
- Qi Zheng has redone the earlier (and reverted) attempt to make slab
shrinking lockless in the series "use refcount+RCU method to implement
lockless slab shrink".
- David Hildenbrand contributes some maintenance work for the rmap code
in the series "Anon rmap cleanups".
- Kefeng Wang does more folio conversions and some maintenance work in
the migration code. Series "mm: migrate: more folio conversion and
unification".
- Matthew Wilcox has fixed an issue in the buffer_head code which was
causing long stalls under some heavy memory/IO loads. Some cleanups
were added on the way. Series "Add and use bdev_getblk()".
- In the series "Use nth_page() in place of direct struct page
manipulation" Zi Yan has fixed a potential issue with the direct
manipulation of hugetlb page frames.
- In the series "mm: hugetlb: Skip initialization of gigantic tail
struct pages if freed by HVO" has improved our handling of gigantic
pages in the hugetlb vmmemmep optimizaton code. This provides
significant boot time improvements when significant amounts of gigantic
pages are in use.
- Matthew Wilcox has sent the series "Small hugetlb cleanups" - code
rationalization and folio conversions in the hugetlb code.
- Yin Fengwei has improved mlock()'s handling of large folios in the
series "support large folio for mlock"
- In the series "Expose swapcache stat for memcg v1" Liu Shixin has
added statistics for memcg v1 users which are available (and useful)
under memcg v2.
- Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable)
prctl so that userspace may direct the kernel to not automatically
propagate the denial to child processes. The series is named "MDWE
without inheritance".
- Kefeng Wang has provided the series "mm: convert numa balancing
functions to use a folio" which does what it says.
- In the series "mm/ksm: add fork-exec support for prctl" Stefan Roesch
makes is possible for a process to propagate KSM treatment across
exec().
- Huang Ying has enhanced memory tiering's calculation of memory
distances. This is used to permit the dax/kmem driver to use "high
bandwidth memory" in addition to Optane Data Center Persistent Memory
Modules (DCPMM). The series is named "memory tiering: calculate
abstract distance based on ACPI HMAT"
- In the series "Smart scanning mode for KSM" Stefan Roesch has
optimized KSM by teaching it to retain and use some historical
information from previous scans.
- Yosry Ahmed has fixed some inconsistencies in memcg statistics in the
series "mm: memcg: fix tracking of pending stats updates values".
- In the series "Implement IOCTL to get and optionally clear info about
PTEs" Peter Xu has added an ioctl to /proc/<pid>/pagemap which permits
us to atomically read-then-clear page softdirty state. This is mainly
used by CRIU.
- Hugh Dickins contributed the series "shmem,tmpfs: general maintenance"
- a bunch of relatively minor maintenance tweaks to this code.
- Matthew Wilcox has increased the use of the VMA lock over file-backed
page faults in the series "Handle more faults under the VMA lock". Some
rationalizations of the fault path became possible as a result.
- In the series "mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()" David Hildenbrand has implemented some cleanups
and folio conversions.
- In the series "various improvements to the GUP interface" Lorenzo
Stoakes has simplified and improved the GUP interface with an eye to
providing groundwork for future improvements.
- Andrey Konovalov has sent along the series "kasan: assorted fixes and
improvements" which does those things.
- Some page allocator maintenance work from Kemeng Shi in the series
"Two minor cleanups to break_down_buddy_pages".
- In thes series "New selftest for mm" Breno Leitao has developed
another MM self test which tickles a race we had between madvise() and
page faults.
- In the series "Add folio_end_read" Matthew Wilcox provides cleanups
and an optimization to the core pagecache code.
- Nhat Pham has added memcg accounting for hugetlb memory in the series
"hugetlb memcg accounting".
- Cleanups and rationalizations to the pagemap code from Lorenzo
Stoakes, in the series "Abstract vma_merge() and split_vma()".
- Audra Mitchell has fixed issues in the procfs page_owner code's new
timestamping feature which was causing some misbehaviours. In the
series "Fix page_owner's use of free timestamps".
- Lorenzo Stoakes has fixed the handling of new mappings of sealed files
in the series "permit write-sealed memfd read-only shared mappings".
- Mike Kravetz has optimized the hugetlb vmemmap optimization in the
series "Batch hugetlb vmemmap modification operations".
- Some buffer_head folio conversions and cleanups from Matthew Wilcox in
the series "Finish the create_empty_buffers() transition".
- As a page allocator performance optimization Huang Ying has added
automatic tuning to the allocator's per-cpu-pages feature, in the series
"mm: PCP high auto-tuning".
- Roman Gushchin has contributed the patchset "mm: improve performance
of accounted kernel memory allocations" which improves their performance
by ~30% as measured by a micro-benchmark.
- folio conversions from Kefeng Wang in the series "mm: convert page
cpupid functions to folios".
- Some kmemleak fixups in Liu Shixin's series "Some bugfix about
kmemleak".
- Qi Zheng has improved our handling of memoryless nodes by keeping them
off the allocation fallback list. This is done in the series "handle
memoryless nodes more appropriately".
- khugepaged conversions from Vishal Moola in the series "Some
khugepaged folio conversions".
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Merge tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"Many singleton patches against the MM code. The patch series which are
included in this merge do the following:
- Kemeng Shi has contributed some compation maintenance work in the
series 'Fixes and cleanups to compaction'
- Joel Fernandes has a patchset ('Optimize mremap during mutual
alignment within PMD') which fixes an obscure issue with mremap()'s
pagetable handling during a subsequent exec(), based upon an
implementation which Linus suggested
- More DAMON/DAMOS maintenance and feature work from SeongJae Park i
the following patch series:
mm/damon: misc fixups for documents, comments and its tracepoint
mm/damon: add a tracepoint for damos apply target regions
mm/damon: provide pseudo-moving sum based access rate
mm/damon: implement DAMOS apply intervals
mm/damon/core-test: Fix memory leaks in core-test
mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval
- In the series 'Do not try to access unaccepted memory' Adrian
Hunter provides some fixups for the recently-added 'unaccepted
memory' feature. To increase the feature's checking coverage. 'Plug
a few gaps where RAM is exposed without checking if it is
unaccepted memory'
- In the series 'cleanups for lockless slab shrink' Qi Zheng has done
some maintenance work which is preparation for the lockless slab
shrinking code
- Qi Zheng has redone the earlier (and reverted) attempt to make slab
shrinking lockless in the series 'use refcount+RCU method to
implement lockless slab shrink'
- David Hildenbrand contributes some maintenance work for the rmap
code in the series 'Anon rmap cleanups'
- Kefeng Wang does more folio conversions and some maintenance work
in the migration code. Series 'mm: migrate: more folio conversion
and unification'
- Matthew Wilcox has fixed an issue in the buffer_head code which was
causing long stalls under some heavy memory/IO loads. Some cleanups
were added on the way. Series 'Add and use bdev_getblk()'
- In the series 'Use nth_page() in place of direct struct page
manipulation' Zi Yan has fixed a potential issue with the direct
manipulation of hugetlb page frames
- In the series 'mm: hugetlb: Skip initialization of gigantic tail
struct pages if freed by HVO' has improved our handling of gigantic
pages in the hugetlb vmmemmep optimizaton code. This provides
significant boot time improvements when significant amounts of
gigantic pages are in use
- Matthew Wilcox has sent the series 'Small hugetlb cleanups' - code
rationalization and folio conversions in the hugetlb code
- Yin Fengwei has improved mlock()'s handling of large folios in the
series 'support large folio for mlock'
- In the series 'Expose swapcache stat for memcg v1' Liu Shixin has
added statistics for memcg v1 users which are available (and
useful) under memcg v2
- Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable)
prctl so that userspace may direct the kernel to not automatically
propagate the denial to child processes. The series is named 'MDWE
without inheritance'
- Kefeng Wang has provided the series 'mm: convert numa balancing
functions to use a folio' which does what it says
- In the series 'mm/ksm: add fork-exec support for prctl' Stefan
Roesch makes is possible for a process to propagate KSM treatment
across exec()
- Huang Ying has enhanced memory tiering's calculation of memory
distances. This is used to permit the dax/kmem driver to use 'high
bandwidth memory' in addition to Optane Data Center Persistent
Memory Modules (DCPMM). The series is named 'memory tiering:
calculate abstract distance based on ACPI HMAT'
- In the series 'Smart scanning mode for KSM' Stefan Roesch has
optimized KSM by teaching it to retain and use some historical
information from previous scans
- Yosry Ahmed has fixed some inconsistencies in memcg statistics in
the series 'mm: memcg: fix tracking of pending stats updates
values'
- In the series 'Implement IOCTL to get and optionally clear info
about PTEs' Peter Xu has added an ioctl to /proc/<pid>/pagemap
which permits us to atomically read-then-clear page softdirty
state. This is mainly used by CRIU
- Hugh Dickins contributed the series 'shmem,tmpfs: general
maintenance', a bunch of relatively minor maintenance tweaks to
this code
- Matthew Wilcox has increased the use of the VMA lock over
file-backed page faults in the series 'Handle more faults under the
VMA lock'. Some rationalizations of the fault path became possible
as a result
- In the series 'mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()' David Hildenbrand has implemented some
cleanups and folio conversions
- In the series 'various improvements to the GUP interface' Lorenzo
Stoakes has simplified and improved the GUP interface with an eye
to providing groundwork for future improvements
- Andrey Konovalov has sent along the series 'kasan: assorted fixes
and improvements' which does those things
- Some page allocator maintenance work from Kemeng Shi in the series
'Two minor cleanups to break_down_buddy_pages'
- In thes series 'New selftest for mm' Breno Leitao has developed
another MM self test which tickles a race we had between madvise()
and page faults
- In the series 'Add folio_end_read' Matthew Wilcox provides cleanups
and an optimization to the core pagecache code
- Nhat Pham has added memcg accounting for hugetlb memory in the
series 'hugetlb memcg accounting'
- Cleanups and rationalizations to the pagemap code from Lorenzo
Stoakes, in the series 'Abstract vma_merge() and split_vma()'
- Audra Mitchell has fixed issues in the procfs page_owner code's new
timestamping feature which was causing some misbehaviours. In the
series 'Fix page_owner's use of free timestamps'
- Lorenzo Stoakes has fixed the handling of new mappings of sealed
files in the series 'permit write-sealed memfd read-only shared
mappings'
- Mike Kravetz has optimized the hugetlb vmemmap optimization in the
series 'Batch hugetlb vmemmap modification operations'
- Some buffer_head folio conversions and cleanups from Matthew Wilcox
in the series 'Finish the create_empty_buffers() transition'
- As a page allocator performance optimization Huang Ying has added
automatic tuning to the allocator's per-cpu-pages feature, in the
series 'mm: PCP high auto-tuning'
- Roman Gushchin has contributed the patchset 'mm: improve
performance of accounted kernel memory allocations' which improves
their performance by ~30% as measured by a micro-benchmark
- folio conversions from Kefeng Wang in the series 'mm: convert page
cpupid functions to folios'
- Some kmemleak fixups in Liu Shixin's series 'Some bugfix about
kmemleak'
- Qi Zheng has improved our handling of memoryless nodes by keeping
them off the allocation fallback list. This is done in the series
'handle memoryless nodes more appropriately'
- khugepaged conversions from Vishal Moola in the series 'Some
khugepaged folio conversions'"
[ bcachefs conflicts with the dynamically allocated shrinkers have been
resolved as per Stephen Rothwell in
https://lore.kernel.org/all/20230913093553.4290421e@canb.auug.org.au/
with help from Qi Zheng.
The clone3 test filtering conflict was half-arsed by yours truly ]
* tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (406 commits)
mm/damon/sysfs: update monitoring target regions for online input commit
mm/damon/sysfs: remove requested targets when online-commit inputs
selftests: add a sanity check for zswap
Documentation: maple_tree: fix word spelling error
mm/vmalloc: fix the unchecked dereference warning in vread_iter()
zswap: export compression failure stats
Documentation: ubsan: drop "the" from article title
mempolicy: migration attempt to match interleave nodes
mempolicy: mmap_lock is not needed while migrating folios
mempolicy: alloc_pages_mpol() for NUMA policy without vma
mm: add page_rmappable_folio() wrapper
mempolicy: remove confusing MPOL_MF_LAZY dead code
mempolicy: mpol_shared_policy_init() without pseudo-vma
mempolicy trivia: use pgoff_t in shared mempolicy tree
mempolicy trivia: slightly more consistent naming
mempolicy trivia: delete those ancient pr_debug()s
mempolicy: fix migrate_pages(2) syscall return nr_failed
kernfs: drop shared NUMA mempolicy hooks
hugetlbfs: drop shared NUMA mempolicy pretence
mm/damon/sysfs-test: add a unit test for damon_sysfs_set_targets()
...
The ia64 architecture gets its well-earned retirement as planned,
now that there is one last (mostly) working release that will
be maintained as an LTS kernel.
The architecture specific system call tables are updated for
the added map_shadow_stack() syscall and to remove references
to the long-gone sys_lookup_dcookie() syscall.
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Merge tag 'asm-generic-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic
Pull ia64 removal and asm-generic updates from Arnd Bergmann:
- The ia64 architecture gets its well-earned retirement as planned,
now that there is one last (mostly) working release that will be
maintained as an LTS kernel.
- The architecture specific system call tables are updated for the
added map_shadow_stack() syscall and to remove references to the
long-gone sys_lookup_dcookie() syscall.
* tag 'asm-generic-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
hexagon: Remove unusable symbols from the ptrace.h uapi
asm-generic: Fix spelling of architecture
arch: Reserve map_shadow_stack() syscall number for all architectures
syscalls: Cleanup references to sys_lookup_dcookie()
Documentation: Drop or replace remaining mentions of IA64
lib/raid6: Drop IA64 support
Documentation: Drop IA64 from feature descriptions
kernel: Drop IA64 support from sig_fault handlers
arch: Remove Itanium (IA-64) architecture
- Add support for several Qualcomm SoC versions and other similar
changes (Christian Marangi, Dmitry Baryshkov, Luca Weiss, Neil
Armstrong, Richard Acayan, Robert Marko, Rohit Agarwal, Stephan
Gerhold and Varadarajan Narayanan).
- Clean up the tegra cpufreq driver (Sumit Gupta).
- Use of_property_read_reg() to parse "reg" in pmac32 driver (Rob
Herring).
- Add support for TI's am62p5 Soc (Bryan Brattlof).
- Make ARM_BRCMSTB_AVS_CPUFREQ depends on !ARM_SCMI_CPUFREQ (Florian
Fainelli).
- Update Kconfig to mention i.MX7 as well (Alexander Stein).
- Revise global turbo disable check in intel_pstate (Srinivas
Pandruvada).
- Carry out initialization of sg_cpu in the schedutil cpufreq governor
in one loop (Liao Chang).
- Simplify the condition for storing 'down_threshold' in the
conservative cpufreq governor (Liao Chang).
- Use fine-grained mutex in the userspace cpufreq governor (Liao
Chang).
- Move is_managed indicator in the userspace cpufreq governor into a
per-policy structure (Liao Chang).
- Rebuild sched-domains when removing cpufreq driver (Pierre Gondois).
- Fix buffer overflow detection in trans_stats() (Christian Marangi).
- Switch to dev_pm_opp_find_freq_(ceil/floor)_indexed() APIs to support
specific devices like UFS which handle multiple clocks through OPP
(Operating Performance Point) framework (Manivannan Sadhasivam).
- Add perf support to the Rockchip DFI (DDR Monitor Module) devfreq-
event driver:
* Generalize rockchip-dfi.c to support new RK3568/RK3588 using
different DDR type (Sascha Hauer).
* Convert DT binding document format to yaml (Sascha Hauer).
* Add perf support for DFI (a unit suitable for measuring DDR
utilization) to rockchip-dfi.c to extend DFI usage (Sascha Hauer).
- Add locking to the OPP handling code in the Mediatek CCI devfreq
driver, because the voltage of shared OPP might be changed by
multiple drivers (Mark Tseng, Dan Carpenter).
- Use device_get_match_data() in the Samsung Exynos PPMU devfreq-event
driver (Rob Herring).
- Extend support for the opp-level beyond required-opps (Ulf Hansson).
- Add dev_pm_opp_find_level_floor() (Krishna chaitanya chundru).
- dt-bindings: Allow opp-peak-kBpsfor kryo CPUs, support Qualcomm Krait
SoCs and document named opp-microvolt property (Bjorn Andersson,
Dmitry Baryshkov and Christian Marangi).
- Fix -Wunsequenced warning _of_add_opp_table_v1() (Nathan Chancellor).
- General cleanup of OPP code (Viresh Kumar).
- Use __get_safe_page() rather than touching the list in hibernation
snapshot code (Brian Geffon).
- Fix symbol export for _SIMPLE_ variants of _PM_OPS() (Raag Jadav).
- Clean up sync_read handling in snapshot_write_next() (Brian Geffon).
- Fix kerneldoc comments for swsusp_check() and swsusp_close() to
better match code (Christoph Hellwig).
- Downgrade BIOS locked limits pr_warn() in the Intel RAPL power
capping driver to pr_debug() (Ville Syrjälä).
- Change the minimum python version for the intel_pstate_tracer utility
from 2.7 to 3.6 (Doug Smythies).
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Merge tag 'pm-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"These add new hardware support (new Qualcomm SoC versions in cpufreq,
RK3568/RK3588 in devfreq), extend the OPP (operating performance
points) framework, improve cpufreq governors, fix issues and clean up
code (most of the changes are in cpufreq and devfreq).
Specifics:
- Add support for several Qualcomm SoC versions and other similar
changes (Christian Marangi, Dmitry Baryshkov, Luca Weiss, Neil
Armstrong, Richard Acayan, Robert Marko, Rohit Agarwal, Stephan
Gerhold and Varadarajan Narayanan)
- Clean up the tegra cpufreq driver (Sumit Gupta)
- Use of_property_read_reg() to parse "reg" in pmac32 driver (Rob
Herring)
- Add support for TI's am62p5 Soc (Bryan Brattlof)
- Make ARM_BRCMSTB_AVS_CPUFREQ depends on !ARM_SCMI_CPUFREQ (Florian
Fainelli)
- Update Kconfig to mention i.MX7 as well (Alexander Stein)
- Revise global turbo disable check in intel_pstate (Srinivas
Pandruvada)
- Carry out initialization of sg_cpu in the schedutil cpufreq
governor in one loop (Liao Chang)
- Simplify the condition for storing 'down_threshold' in the
conservative cpufreq governor (Liao Chang)
- Use fine-grained mutex in the userspace cpufreq governor (Liao
Chang)
- Move is_managed indicator in the userspace cpufreq governor into a
per-policy structure (Liao Chang)
- Rebuild sched-domains when removing cpufreq driver (Pierre Gondois)
- Fix buffer overflow detection in trans_stats() (Christian Marangi)
- Switch to dev_pm_opp_find_freq_(ceil/floor)_indexed() APIs to
support specific devices like UFS which handle multiple clocks
through OPP (Operating Performance Point) framework (Manivannan
Sadhasivam)
- Add perf support to the Rockchip DFI (DDR Monitor Module) devfreq-
event driver:
* Generalize rockchip-dfi.c to support new RK3568/RK3588 using
different DDR type (Sascha Hauer).
* Convert DT binding document format to yaml (Sascha Hauer).
* Add perf support for DFI (a unit suitable for measuring DDR
utilization) to rockchip-dfi.c to extend DFI usage (Sascha
Hauer)
- Add locking to the OPP handling code in the Mediatek CCI devfreq
driver, because the voltage of shared OPP might be changed by
multiple drivers (Mark Tseng, Dan Carpenter)
- Use device_get_match_data() in the Samsung Exynos PPMU
devfreq-event driver (Rob Herring)
- Extend support for the opp-level beyond required-opps (Ulf Hansson)
- Add dev_pm_opp_find_level_floor() (Krishna chaitanya chundru)
- dt-bindings: Allow opp-peak-kBpsfor kryo CPUs, support Qualcomm
Krait SoCs and document named opp-microvolt property (Bjorn
Andersson, Dmitry Baryshkov and Christian Marangi)
- Fix -Wunsequenced warning _of_add_opp_table_v1() (Nathan
Chancellor)
- General cleanup of OPP code (Viresh Kumar)
- Use __get_safe_page() rather than touching the list in hibernation
snapshot code (Brian Geffon)
- Fix symbol export for _SIMPLE_ variants of _PM_OPS() (Raag Jadav)
- Clean up sync_read handling in snapshot_write_next() (Brian Geffon)
- Fix kerneldoc comments for swsusp_check() and swsusp_close() to
better match code (Christoph Hellwig)
- Downgrade BIOS locked limits pr_warn() in the Intel RAPL power
capping driver to pr_debug() (Ville Syrjälä)
- Change the minimum python version for the intel_pstate_tracer
utility from 2.7 to 3.6 (Doug Smythies)"
* tag 'pm-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (82 commits)
dt-bindings: cpufreq: qcom-hw: document SM8650 CPUFREQ Hardware
cpufreq: arm: Kconfig: Add i.MX7 to supported SoC for ARM_IMX_CPUFREQ_DT
cpufreq: qcom-nvmem: add support for IPQ8064
cpufreq: qcom-nvmem: also accept operating-points-v2-krait-cpu
cpufreq: qcom-nvmem: drop pvs_ver for format a fuses
dt-bindings: cpufreq: qcom-cpufreq-nvmem: Document krait-cpu
cpufreq: qcom-nvmem: add support for IPQ6018
dt-bindings: cpufreq: qcom-cpufreq-nvmem: document IPQ6018
cpufreq: qcom-nvmem: Add MSM8909
cpufreq: qcom-nvmem: Simplify driver data allocation
powercap: intel_rapl: Downgrade BIOS locked limits pr_warn() to pr_debug()
cpufreq: stats: Fix buffer overflow detection in trans_stats()
dt-bindings: devfreq: event: rockchip,dfi: Add rk3588 support
dt-bindings: devfreq: event: rockchip,dfi: Add rk3568 support
dt-bindings: devfreq: event: convert Rockchip DFI binding to yaml
PM / devfreq: rockchip-dfi: add support for RK3588
PM / devfreq: rockchip-dfi: account for multiple DDRMON_CTRL registers
PM / devfreq: rockchip-dfi: make register stride SoC specific
PM / devfreq: rockchip-dfi: Add perf support
PM / devfreq: rockchip-dfi: give variable a better name
...
- Fair scheduler (SCHED_OTHER) improvements:
- Remove the old and now unused SIS_PROP code & option
- Scan cluster before LLC in the wake-up path
- Use candidate prev/recent_used CPU if scanning failed for cluster wakeup
- NUMA scheduling improvements:
- Improve the VMA access-PID code to better skip/scan VMAs
- Extend tracing to cover VMA-skipping decisions
- Improve/fix the recently introduced sched_numa_find_nth_cpu() code
- Generalize numa_map_to_online_node()
- Energy scheduling improvements:
- Remove the EM_MAX_COMPLEXITY limit
- Add tracepoints to track energy computation
- Make the behavior of the 'sched_energy_aware' sysctl more consistent
- Consolidate and clean up access to a CPU's max compute capacity
- Fix uclamp code corner cases
- RT scheduling improvements:
- Drive dl_rq->overloaded with dl_rq->pushable_dl_tasks updates
- Drive the ->rto_mask with rt_rq->pushable_tasks updates
- Scheduler scalability improvements:
- Rate-limit updates to tg->load_avg
- On x86 disable IBRS when CPU is offline to improve single-threaded performance
- Micro-optimize in_task() and in_interrupt()
- Micro-optimize the PSI code
- Avoid updating PSI triggers and ->rtpoll_total when there are no state changes
- Core scheduler infrastructure improvements:
- Use saved_state to reduce some spurious freezer wakeups
- Bring in a handful of fast-headers improvements to scheduler headers
- Make the scheduler UAPI headers more widely usable by user-space
- Simplify the control flow of scheduler syscalls by using lock guards
- Fix sched_setaffinity() vs. CPU hotplug race
- Scheduler debuggability improvements:
- Disallow writing invalid values to sched_rt_period_us
- Fix a race in the rq-clock debugging code triggering warnings
- Fix a warning in the bandwidth distribution code
- Micro-optimize in_atomic_preempt_off() checks
- Enforce that the tasklist_lock is held in for_each_thread()
- Print the TGID in sched_show_task()
- Remove the /proc/sys/kernel/sched_child_runs_first sysctl
- Misc cleanups & fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Fair scheduler (SCHED_OTHER) improvements:
- Remove the old and now unused SIS_PROP code & option
- Scan cluster before LLC in the wake-up path
- Use candidate prev/recent_used CPU if scanning failed for cluster
wakeup
NUMA scheduling improvements:
- Improve the VMA access-PID code to better skip/scan VMAs
- Extend tracing to cover VMA-skipping decisions
- Improve/fix the recently introduced sched_numa_find_nth_cpu() code
- Generalize numa_map_to_online_node()
Energy scheduling improvements:
- Remove the EM_MAX_COMPLEXITY limit
- Add tracepoints to track energy computation
- Make the behavior of the 'sched_energy_aware' sysctl more
consistent
- Consolidate and clean up access to a CPU's max compute capacity
- Fix uclamp code corner cases
RT scheduling improvements:
- Drive dl_rq->overloaded with dl_rq->pushable_dl_tasks updates
- Drive the ->rto_mask with rt_rq->pushable_tasks updates
Scheduler scalability improvements:
- Rate-limit updates to tg->load_avg
- On x86 disable IBRS when CPU is offline to improve single-threaded
performance
- Micro-optimize in_task() and in_interrupt()
- Micro-optimize the PSI code
- Avoid updating PSI triggers and ->rtpoll_total when there are no
state changes
Core scheduler infrastructure improvements:
- Use saved_state to reduce some spurious freezer wakeups
- Bring in a handful of fast-headers improvements to scheduler
headers
- Make the scheduler UAPI headers more widely usable by user-space
- Simplify the control flow of scheduler syscalls by using lock
guards
- Fix sched_setaffinity() vs. CPU hotplug race
Scheduler debuggability improvements:
- Disallow writing invalid values to sched_rt_period_us
- Fix a race in the rq-clock debugging code triggering warnings
- Fix a warning in the bandwidth distribution code
- Micro-optimize in_atomic_preempt_off() checks
- Enforce that the tasklist_lock is held in for_each_thread()
- Print the TGID in sched_show_task()
- Remove the /proc/sys/kernel/sched_child_runs_first sysctl
... and misc cleanups & fixes"
* tag 'sched-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (82 commits)
sched/fair: Remove SIS_PROP
sched/fair: Use candidate prev/recent_used CPU if scanning failed for cluster wakeup
sched/fair: Scan cluster before scanning LLC in wake-up path
sched: Add cpus_share_resources API
sched/core: Fix RQCF_ACT_SKIP leak
sched/fair: Remove unused 'curr' argument from pick_next_entity()
sched/nohz: Update comments about NEWILB_KICK
sched/fair: Remove duplicate #include
sched/psi: Update poll => rtpoll in relevant comments
sched: Make PELT acronym definition searchable
sched: Fix stop_one_cpu_nowait() vs hotplug
sched/psi: Bail out early from irq time accounting
sched/topology: Rename 'DIE' domain to 'PKG'
sched/psi: Delete the 'update_total' function parameter from update_triggers()
sched/psi: Avoid updating PSI triggers and ->rtpoll_total when there are no state changes
sched/headers: Remove comment referring to rq::cpu_load, since this has been removed
sched/numa: Complete scanning of inactive VMAs when there is no alternative
sched/numa: Complete scanning of partial VMAs regardless of PID activity
sched/numa: Move up the access pid reset logic
sched/numa: Trace decisions related to skipping VMAs
...
- Futex improvements:
- Add the 'futex2' syscall ABI, which is an attempt to get away from the
multiplex syscall and adds a little room for extentions, while lifting
some limitations.
- Fix futex PI recursive rt_mutex waiter state bug
- Fix inter-process shared futexes on no-MMU systems
- Use folios instead of pages
- Micro-optimizations of locking primitives:
- Improve arch_spin_value_unlocked() on asm-generic ticket spinlock
architectures, to improve lockref code generation.
- Improve the x86-32 lockref_get_not_zero() main loop by adding
build-time CMPXCHG8B support detection for the relevant lockref code,
and by better interfacing the CMPXCHG8B assembly code with the compiler.
- Introduce arch_sync_try_cmpxchg() on x86 to improve sync_try_cmpxchg()
code generation. Convert some sync_cmpxchg() users to sync_try_cmpxchg().
- Micro-optimize rcuref_put_slowpath()
- Locking debuggability improvements:
- Improve CONFIG_DEBUG_RT_MUTEXES=y to have a fast-path as well
- Enforce atomicity of sched_submit_work(), which is de-facto atomic but
was un-enforced previously.
- Extend <linux/cleanup.h>'s no_free_ptr() with __must_check semantics
- Fix ww_mutex self-tests
- Clean up const-propagation in <linux/seqlock.h> and simplify
the API-instantiation macros a bit.
- RT locking improvements:
- Provide the rt_mutex_*_schedule() primitives/helpers and use them
in the rtmutex code to avoid recursion vs. rtlock on the PI state.
- Add nested blocking lockdep asserts to rt_mutex_lock(), rtlock_lock()
and rwbase_read_lock().
- Plus misc fixes & cleanups
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Info Molnar:
"Futex improvements:
- Add the 'futex2' syscall ABI, which is an attempt to get away from
the multiplex syscall and adds a little room for extentions, while
lifting some limitations.
- Fix futex PI recursive rt_mutex waiter state bug
- Fix inter-process shared futexes on no-MMU systems
- Use folios instead of pages
Micro-optimizations of locking primitives:
- Improve arch_spin_value_unlocked() on asm-generic ticket spinlock
architectures, to improve lockref code generation
- Improve the x86-32 lockref_get_not_zero() main loop by adding
build-time CMPXCHG8B support detection for the relevant lockref
code, and by better interfacing the CMPXCHG8B assembly code with
the compiler
- Introduce arch_sync_try_cmpxchg() on x86 to improve
sync_try_cmpxchg() code generation. Convert some sync_cmpxchg()
users to sync_try_cmpxchg().
- Micro-optimize rcuref_put_slowpath()
Locking debuggability improvements:
- Improve CONFIG_DEBUG_RT_MUTEXES=y to have a fast-path as well
- Enforce atomicity of sched_submit_work(), which is de-facto atomic
but was un-enforced previously.
- Extend <linux/cleanup.h>'s no_free_ptr() with __must_check
semantics
- Fix ww_mutex self-tests
- Clean up const-propagation in <linux/seqlock.h> and simplify the
API-instantiation macros a bit
RT locking improvements:
- Provide the rt_mutex_*_schedule() primitives/helpers and use them
in the rtmutex code to avoid recursion vs. rtlock on the PI state.
- Add nested blocking lockdep asserts to rt_mutex_lock(),
rtlock_lock() and rwbase_read_lock()
.. plus misc fixes & cleanups"
* tag 'locking-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
futex: Don't include process MM in futex key on no-MMU
locking/seqlock: Fix grammar in comment
alpha: Fix up new futex syscall numbers
locking/seqlock: Propagate 'const' pointers within read-only methods, remove forced type casts
locking/lockdep: Fix string sizing bug that triggers a format-truncation compiler-warning
locking/seqlock: Change __seqprop() to return the function pointer
locking/seqlock: Simplify SEQCOUNT_LOCKNAME()
locking/atomics: Use atomic_try_cmpxchg_release() to micro-optimize rcuref_put_slowpath()
locking/atomic, xen: Use sync_try_cmpxchg() instead of sync_cmpxchg()
locking/atomic/x86: Introduce arch_sync_try_cmpxchg()
locking/atomic: Add generic support for sync_try_cmpxchg() and its fallback
locking/seqlock: Fix typo in comment
futex/requeue: Remove unnecessary ‘NULL’ initialization from futex_proxy_trylock_atomic()
locking/local, arch: Rewrite local_add_unless() as a static inline function
locking/debug: Fix debugfs API return value checks to use IS_ERR()
locking/ww_mutex/test: Make sure we bail out instead of livelock
locking/ww_mutex/test: Fix potential workqueue corruption
locking/ww_mutex/test: Use prng instead of rng to avoid hangs at bootup
futex: Add sys_futex_requeue()
futex: Add flags2 argument to futex_requeue()
...
Merge cpufreq updates for 6.7-rc1:
- Add support for several Qualcomm SoC versions and other similar
changes (Christian Marangi, Dmitry Baryshkov, Luca Weiss, Neil
Armstrong, Richard Acayan, Robert Marko, Rohit Agarwal, Stephan
Gerhold and Varadarajan Narayanan).
- Clean up the tegra cpufreq driver (Sumit Gupta).
- Use of_property_read_reg() to parse "reg" in pmac32 driver (Rob
Herring).
- Add support for TI's am62p5 Soc (Bryan Brattlof).
- Make ARM_BRCMSTB_AVS_CPUFREQ depends on !ARM_SCMI_CPUFREQ (Florian
Fainelli).
- Update Kconfig to mention i.MX7 as well (Alexander Stein).
- Revise global turbo disable check in intel_pstate (Srinivas
Pandruvada).
- Carry out initialization of sg_cpu in the schedutil cpufreq governor
in one loop (Liao Chang).
- Simplify the condition for storing 'down_threshold' in the
conservative cpufreq governor (Liao Chang).
- Use fine-grained mutex in the userspace cpufreq governor (Liao
Chang).
- Move is_managed indicator in the userspace cpufreq governor into a
per-policy structure (Liao Chang).
- Rebuild sched-domains when removing cpufreq driver (Pierre Gondois).
- Fix buffer overflow detection in trans_stats() (Christian Marangi).
* pm-cpufreq: (32 commits)
dt-bindings: cpufreq: qcom-hw: document SM8650 CPUFREQ Hardware
cpufreq: arm: Kconfig: Add i.MX7 to supported SoC for ARM_IMX_CPUFREQ_DT
cpufreq: qcom-nvmem: add support for IPQ8064
cpufreq: qcom-nvmem: also accept operating-points-v2-krait-cpu
cpufreq: qcom-nvmem: drop pvs_ver for format a fuses
dt-bindings: cpufreq: qcom-cpufreq-nvmem: Document krait-cpu
cpufreq: qcom-nvmem: add support for IPQ6018
dt-bindings: cpufreq: qcom-cpufreq-nvmem: document IPQ6018
cpufreq: qcom-nvmem: Add MSM8909
cpufreq: qcom-nvmem: Simplify driver data allocation
cpufreq: stats: Fix buffer overflow detection in trans_stats()
dt-bindings: cpufreq: cpufreq-qcom-hw: Add SDX75 compatible
cpufreq: ARM_BRCMSTB_AVS_CPUFREQ cannot be used with ARM_SCMI_CPUFREQ
cpufreq: ti-cpufreq: Add opp support for am62p5 SoCs
cpufreq: dt-platdev: add am62p5 to blocklist
cpufreq: tegra194: remove redundant AND with cpu_online_mask
cpufreq: tegra194: use refclk delta based loop instead of udelay
cpufreq: tegra194: save CPU data to avoid repeated SMP calls
cpufreq: Rebuild sched-domains when removing cpufreq driver
cpufreq: userspace: Move is_managed indicator into per-policy structure
...
Convert to use folio_xchg_last_cpupid() in should_numa_migrate_memory().
Link: https://lkml.kernel.org/r/20231018140806.2783514-14-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Convert to use folio_xchg_access_time() in numa_hint_fault_latency().
Link: https://lkml.kernel.org/r/20231018140806.2783514-9-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Chen Yu reports a hackbench regression of cluster wakeup when
hackbench threads equal to the CPU number [1]. Analysis shows
it's because we wake up more on the target CPU even if the
prev_cpu is a good wakeup candidate and leads to the decrease
of the CPU utilization.
Generally if the task's prev_cpu is idle we'll wake up the task
on it without scanning. On cluster machines we'll try to wake up
the task in the same cluster of the target for better cache
affinity, so if the prev_cpu is idle but not sharing the same
cluster with the target we'll still try to find an idle CPU within
the cluster. This will improve the performance at low loads on
cluster machines. But in the issue above, if the prev_cpu is idle
but not in the cluster with the target CPU, we'll try to scan an
idle one in the cluster. But since the system is busy, we're
likely to fail the scanning and use target instead, even if
the prev_cpu is idle. Then leads to the regression.
This patch solves this in 2 steps:
o record the prev_cpu/recent_used_cpu if they're good wakeup
candidates but not sharing the cluster with the target.
o on scanning failure use the prev_cpu/recent_used_cpu if
they're recorded as idle
[1] https://lore.kernel.org/all/ZGzDLuVaHR1PAYDt@chenyu5-mobl1/
Closes: https://lore.kernel.org/all/ZGsLy83wPIpamy6x@chenyu5-mobl1/
Reported-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Tested-and-reviewed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20231019033323.54147-4-yangyicong@huawei.com
For platforms having clusters like Kunpeng920, CPUs within the same cluster
have lower latency when synchronizing and accessing shared resources like
cache. Thus, this patch tries to find an idle cpu within the cluster of the
target CPU before scanning the whole LLC to gain lower latency. This
will be implemented in 2 steps in select_idle_sibling():
1. When the prev_cpu/recent_used_cpu are good wakeup candidates, use them
if they're sharing cluster with the target CPU. Otherwise trying to
scan for an idle CPU in the target's cluster.
2. Scanning the cluster prior to the LLC of the target CPU for an
idle CPU to wakeup.
Testing has been done on Kunpeng920 by pinning tasks to one numa and two
numa. On Kunpeng920, Each numa has 8 clusters and each cluster has 4 CPUs.
With this patch, We noticed enhancement on tbench and netperf within one
numa or cross two numa on top of tip-sched-core commit
9b46f1abc6d4 ("sched/debug: Print 'tgid' in sched_show_task()")
tbench results (node 0):
baseline patched
1: 327.2833 372.4623 ( 13.80%)
4: 1320.5933 1479.8833 ( 12.06%)
8: 2638.4867 2921.5267 ( 10.73%)
16: 5282.7133 5891.5633 ( 11.53%)
32: 9810.6733 9877.3400 ( 0.68%)
64: 7408.9367 7447.9900 ( 0.53%)
128: 6203.2600 6191.6500 ( -0.19%)
tbench results (node 0-1):
baseline patched
1: 332.0433 372.7223 ( 12.25%)
4: 1325.4667 1477.6733 ( 11.48%)
8: 2622.9433 2897.9967 ( 10.49%)
16: 5218.6100 5878.2967 ( 12.64%)
32: 10211.7000 11494.4000 ( 12.56%)
64: 13313.7333 16740.0333 ( 25.74%)
128: 13959.1000 14533.9000 ( 4.12%)
netperf results TCP_RR (node 0):
baseline patched
1: 76546.5033 90649.9867 ( 18.42%)
4: 77292.4450 90932.7175 ( 17.65%)
8: 77367.7254 90882.3467 ( 17.47%)
16: 78519.9048 90938.8344 ( 15.82%)
32: 72169.5035 72851.6730 ( 0.95%)
64: 25911.2457 25882.2315 ( -0.11%)
128: 10752.6572 10768.6038 ( 0.15%)
netperf results TCP_RR (node 0-1):
baseline patched
1: 76857.6667 90892.2767 ( 18.26%)
4: 78236.6475 90767.3017 ( 16.02%)
8: 77929.6096 90684.1633 ( 16.37%)
16: 77438.5873 90502.5787 ( 16.87%)
32: 74205.6635 88301.5612 ( 19.00%)
64: 69827.8535 71787.6706 ( 2.81%)
128: 25281.4366 25771.3023 ( 1.94%)
netperf results UDP_RR (node 0):
baseline patched
1: 96869.8400 110800.8467 ( 14.38%)
4: 97744.9750 109680.5425 ( 12.21%)
8: 98783.9863 110409.9637 ( 11.77%)
16: 99575.0235 110636.2435 ( 11.11%)
32: 95044.7250 97622.8887 ( 2.71%)
64: 32925.2146 32644.4991 ( -0.85%)
128: 12859.2343 12824.0051 ( -0.27%)
netperf results UDP_RR (node 0-1):
baseline patched
1: 97202.4733 110190.1200 ( 13.36%)
4: 95954.0558 106245.7258 ( 10.73%)
8: 96277.1958 105206.5304 ( 9.27%)
16: 97692.7810 107927.2125 ( 10.48%)
32: 79999.6702 103550.2999 ( 29.44%)
64: 80592.7413 87284.0856 ( 8.30%)
128: 27701.5770 29914.5820 ( 7.99%)
Note neither Kunpeng920 nor x86 Jacobsville supports SMT, so the SMT branch
in the code has not been tested but it supposed to work.
Chen Yu also noticed this will improve the performance of tbench and
netperf on a 24 CPUs Jacobsville machine, there are 4 CPUs in one
cluster sharing L2 Cache.
[https://lore.kernel.org/lkml/Ytfjs+m1kUs0ScSn@worktop.programming.kicks-ass.net]
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-and-reviewed-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: Yicong Yang <yangyicong@hisilicon.com>
Link: https://lkml.kernel.org/r/20231019033323.54147-3-yangyicong@huawei.com
Add cpus_share_resources() API. This is the preparation for the
optimization of select_idle_cpu() on platforms with cluster scheduler
level.
On a machine with clusters cpus_share_resources() will test whether
two cpus are within the same cluster. On a non-cluster machine it
will behaves the same as cpus_share_cache(). So we use "resources"
here for cache resources.
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-and-reviewed-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lkml.kernel.org/r/20231019033323.54147-2-yangyicong@huawei.com
Igor Raits and Bagas Sanjaya report a RQCF_ACT_SKIP leak warning.
This warning may be triggered in the following situations:
CPU0 CPU1
__schedule()
*rq->clock_update_flags <<= 1;* unregister_fair_sched_group()
pick_next_task_fair+0x4a/0x410 destroy_cfs_bandwidth()
newidle_balance+0x115/0x3e0 for_each_possible_cpu(i) *i=0*
rq_unpin_lock(this_rq, rf) __cfsb_csd_unthrottle()
raw_spin_rq_unlock(this_rq)
rq_lock(*CPU0_rq*, &rf)
rq_clock_start_loop_update()
rq->clock_update_flags & RQCF_ACT_SKIP <--
raw_spin_rq_lock(this_rq)
The purpose of RQCF_ACT_SKIP is to skip the update rq clock,
but the update is very early in __schedule(), but we clear
RQCF_*_SKIP very late, causing it to span that gap above
and triggering this warning.
In __schedule() we can clear the RQCF_*_SKIP flag immediately
after update_rq_clock() to avoid this RQCF_ACT_SKIP leak warning.
And set rq->clock_update_flags to RQCF_UPDATED to avoid
rq->clock_update_flags < RQCF_ACT_SKIP warning that may be triggered later.
Fixes: ebb83d84e4 ("sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle()")
Closes: https://lore.kernel.org/all/20230913082424.73252-1-jiahao.os@bytedance.com
Reported-by: Igor Raits <igor.raits@gmail.com>
Reported-by: Bagas Sanjaya <bagasdotme@gmail.com>
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/a5dd536d-041a-2ce9-f4b7-64d8d85c86dc@gmail.com
The 'curr' argument of pick_next_entity() has become unused after
the EEVDF changes.
[ mingo: Updated the changelog. ]
Signed-off-by: Yiwei Lin <s921975628@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231020055617.42064-1-s921975628@gmail.com
How ILB is triggered without IPIs is cryptic. Out of mercy for future
code readers, document it in code comments.
The comments are derived from a discussion with Vincent in a past
review.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231020014031.919742-2-joel@joelfernandes.org
__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.
Also, mark some stuff as "const" and "__init" while I'm at it.
[akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning]
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There are no users of wait bookmarks left, so simplify the wait
code by removing them.
Link: https://lkml.kernel.org/r/20231010035829.544242-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Benjamin Segall <bsegall@google.com>
Cc: Bin Lai <sclaibin@gmail.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The cpupid (or access time) is stored in the head page for THP, so it is
safely to make should_numa_migrate_memory() and numa_hint_fault_latency()
to take a folio. This is in preparation for large folio numa balancing.
Link: https://lkml.kernel.org/r/20230921074417.24004-7-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The PSI trigger code is now making a distinction between privileged and
unprivileged triggers, after the following commit:
65457b74aa ("sched/psi: Rename existing poll members in preparation")
But some comments have not been modified along with the code, so they
need to be updated.
This will help readers better understand the code.
Signed-off-by: Fan Yu <fan.yu9@zte.com.cn>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Peter Ziljstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/202310161920399921184@zte.com.cn
The PELT acronym definition can be found right at the top of
kernel/sched/pelt.c (of course), but it cannot be found through use of
grep -r PELT kernel/sched/
Add the acronym "(PELT)" after "Per Entity Load Tracking" at the top of
the source file.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231012125824.1260774-1-mathieu.desnoyers@efficios.com
Kuyo reported sporadic failures on a sched_setaffinity() vs CPU
hotplug stress-test -- notably affine_move_task() remains stuck in
wait_for_completion(), leading to a hung-task detector warning.
Specifically, it was reported that stop_one_cpu_nowait(.fn =
migration_cpu_stop) returns false -- this stopper is responsible for
the matching complete().
The race scenario is:
CPU0 CPU1
// doing _cpu_down()
__set_cpus_allowed_ptr()
task_rq_lock();
takedown_cpu()
stop_machine_cpuslocked(take_cpu_down..)
<PREEMPT: cpu_stopper_thread()
MULTI_STOP_PREPARE
...
__set_cpus_allowed_ptr_locked()
affine_move_task()
task_rq_unlock();
<PREEMPT: cpu_stopper_thread()\>
ack_state()
MULTI_STOP_RUN
take_cpu_down()
__cpu_disable();
stop_machine_park();
stopper->enabled = false;
/>
/>
stop_one_cpu_nowait(.fn = migration_cpu_stop);
if (stopper->enabled) // false!!!
That is, by doing stop_one_cpu_nowait() after dropping rq-lock, the
stopper thread gets a chance to preempt and allows the cpu-down for
the target CPU to complete.
OTOH, since stop_one_cpu_nowait() / cpu_stop_queue_work() needs to
issue a wakeup, it must not be ran under the scheduler locks.
Solve this apparent contradiction by keeping preemption disabled over
the unlock + queue_stopper combination:
preempt_disable();
task_rq_unlock(...);
if (!stop_pending)
stop_one_cpu_nowait(...)
preempt_enable();
This respects the lock ordering contraints while still avoiding the
above race. That is, if we find the CPU is online under rq-lock, the
targeted stop_one_cpu_nowait() must succeed.
Apply this pattern to all similar stop_one_cpu_nowait() invocations.
Fixes: 6d337eab04 ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()")
Reported-by: "Kuyo Chang (張建文)" <Kuyo.Chang@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: "Kuyo Chang (張建文)" <Kuyo.Chang@mediatek.com>
Link: https://lkml.kernel.org/r/20231010200442.GA16515@noisy.programming.kicks-ass.net
We could bail out early when psi was disabled.
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Link: https://lore.kernel.org/r/20230926115722.467833-1-haifeng.xu@shopee.com
While reworking the x86 topology code Thomas tripped over creating a 'DIE' domain
for the package mask. :-)
Since these names are CONFIG_SCHED_DEBUG=y only, rename them to make the
name less ambiguous.
[ Shrikanth Hegde: rename on s390 as well. ]
[ Valentin Schneider: also rename it in the comments. ]
[ mingo: port to recent kernels & find all remaining occurances. ]
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Valentin Schneider <vschneid@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230712141056.GI3100107@hirez.programming.kicks-ass.net
The 'update_total' parameter of update_triggers() is always true after the
previous commit:
80cc1d1d5e ("sched/psi: Avoid updating PSI triggers and ->rtpoll_total when there are no state changes")
If the 'changed_states & group->rtpoll_states' condition is true,
'new_stall' in update_triggers() will be true, and then 'update_total'
should also be true.
So update_total is redundant - remove it.
[ mingo: Changelog updates ]
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Peter Ziljstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/202310101645437859599@zte.com.cn
When psimon wakes up and there are no state changes for ->rtpoll_states,
it's unnecessary to update triggers and ->rtpoll_total because the pressures
being monitored by the user have not changed.
This will help to slightly reduce unnecessary computations of PSI.
[ mingo: Changelog updates ]
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Peter Ziljstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/202310101641075436843@zte.com.cn
There is a comment that refers to cpu_load, however, this cpu_load was
removed with:
55627e3cd2 ("sched/core: Remove rq->cpu_load[]")
... back in 2019. The comment does not make sense with respect to this
removed array, so remove the comment.
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231010155744.1381065-1-colin.i.king@gmail.com
VMAs are skipped if there is no recent fault activity but this represents
a chicken-and-egg problem as there may be no fault activity if the PTEs
are never updated to trap NUMA hints. There is an indirect reliance on
scanning to be forced early in the lifetime of a task but this may fail
to detect changes in phase behaviour. Force inactive VMAs to be scanned
when all other eligible VMAs have been updated within the same scan
sequence.
Test results in general look good with some changes in performance, both
negative and positive, depending on whether the additional scanning and
faulting was beneficial or not to the workload. The autonuma benchmark
workload NUMA01_THREADLOCAL was picked for closer examination. The workload
creates two processes with numerous threads and thread-local storage that
is zero-filled in a loop. It exercises the corner case where unrelated
threads may skip VMAs that are thread-local to another thread and still
has some VMAs that inactive while the workload executes.
The VMA skipping activity frequency with and without the patch:
6.6.0-rc2-sched-numabtrace-v1
=============================
649 reason=scan_delay
9,094 reason=unsuitable
48,915 reason=shared_ro
143,919 reason=inaccessible
193,050 reason=pid_inactive
6.6.0-rc2-sched-numabselective-v1
=============================
146 reason=seq_completed
622 reason=ignore_pid_inactive
624 reason=scan_delay
6,570 reason=unsuitable
16,101 reason=shared_ro
27,608 reason=inaccessible
41,939 reason=pid_inactive
Note that with the patch applied, the PID activity is ignored
(ignore_pid_inactive) to ensure a VMA with some activity is completely
scanned. In addition, a small number of VMAs are scanned when no other
eligible VMA is available during a single scan window (seq_completed).
The number of times a VMA is skipped due to no PID activity from the
scanning task (pid_inactive) drops dramatically. It is expected that
this will increase the number of PTEs updated for NUMA hinting faults
as well as hinting faults but these represent PTEs that would otherwise
have been missed. The tradeoff is scan+fault overhead versus improving
locality due to migration.
On a 2-socket Cascade Lake test machine, the time to complete the
workload is as follows;
6.6.0-rc2 6.6.0-rc2
sched-numabtrace-v1 sched-numabselective-v1
Min elsp-NUMA01_THREADLOCAL 174.22 ( 0.00%) 117.64 ( 32.48%)
Amean elsp-NUMA01_THREADLOCAL 175.68 ( 0.00%) 123.34 * 29.79%*
Stddev elsp-NUMA01_THREADLOCAL 1.20 ( 0.00%) 4.06 (-238.20%)
CoeffVar elsp-NUMA01_THREADLOCAL 0.68 ( 0.00%) 3.29 (-381.70%)
Max elsp-NUMA01_THREADLOCAL 177.18 ( 0.00%) 128.03 ( 27.74%)
The time to complete the workload is reduced by almost 30%:
6.6.0-rc2 6.6.0-rc2
sched-numabtrace-v1 sched-numabselective-v1 /
Duration User 91201.80 63506.64
Duration System 2015.53 1819.78
Duration Elapsed 1234.77 868.37
In this specific case, system CPU time was not increased but it's not
universally true.
From vmstat, the NUMA scanning and fault activity is as follows;
6.6.0-rc2 6.6.0-rc2
sched-numabtrace-v1 sched-numabselective-v1
Ops NUMA base-page range updates 64272.00 26374386.00
Ops NUMA PTE updates 36624.00 55538.00
Ops NUMA PMD updates 54.00 51404.00
Ops NUMA hint faults 15504.00 75786.00
Ops NUMA hint local faults % 14860.00 56763.00
Ops NUMA hint local percent 95.85 74.90
Ops NUMA pages migrated 1629.00 6469222.00
Both the number of PTE updates and hint faults is dramatically
increased. While this is superficially unfortunate, it represents
ranges that were simply skipped without the patch. As a result
of the scanning and hinting faults, many more pages were also
migrated but as the time to completion is reduced, the overhead
is offset by the gain.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Raghavendra K T <raghavendra.kt@amd.com>
Link: https://lore.kernel.org/r/20231010083143.19593-7-mgorman@techsingularity.net
NUMA Balancing skips VMAs when the current task has not trapped a NUMA
fault within the VMA. If the VMA is skipped then mm->numa_scan_offset
advances and a task that is trapping faults within the VMA may never
fully update PTEs within the VMA.
Force tasks to update PTEs for partially scanned PTEs. The VMA will
be tagged for NUMA hints by some task but this removes some of the
benefit of tracking PID activity within a VMA. A follow-on patch
will mitigate this problem.
The test cases and machines evaluated did not trigger the corner case so
the performance results are neutral with only small changes within the
noise from normal test-to-test variance. However, the next patch makes
the corner case easier to trigger.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Raghavendra K T <raghavendra.kt@amd.com>
Link: https://lore.kernel.org/r/20231010083143.19593-6-mgorman@techsingularity.net
Recent NUMA hinting faulting activity is reset approximately every
VMA_PID_RESET_PERIOD milliseconds. However, if the current task has not
accessed a VMA then the reset check is missed and the reset is potentially
deferred forever. Check if the PID activity information should be reset
before checking if the current task recently trapped a NUMA hinting fault.
[ mgorman@techsingularity.net: Rewrite changelog ]
Suggested-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231010083143.19593-5-mgorman@techsingularity.net
NUMA balancing skips or scans VMAs for a variety of reasons. In preparation
for completing scans of VMAs regardless of PID access, trace the reasons
why a VMA was skipped. In a later patch, the tracing will be used to track
if a VMA was forcibly scanned.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231010083143.19593-4-mgorman@techsingularity.net
The access_pids[] field name is somewhat ambiguous as no PIDs are accessed.
Similarly, it's not clear that next_pid_reset is related to access_pids[].
Rename the fields to more accurately reflect their purpose.
[ mingo: Rename in the comments too. ]
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231010083143.19593-3-mgorman@techsingularity.net
Move it out of the .c file into the shared scheduler-internal header file,
to gain type-checking.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20231009060037.170765-3-sshegde@linux.vnet.ibm.com
The 'sched_energy_aware' sysctl is available for the admin to disable/enable
energy aware scheduling(EAS). EAS is enabled only if few conditions are
met by the platform. They are, asymmetric CPU capacity, no SMT,
schedutil CPUfreq governor, frequency invariant load tracking etc.
A platform may boot without EAS capability, but could gain such
capability at runtime. For example, changing/registering the cpufreq
governor to schedutil.
At present, though platform doesn't support EAS, this sysctl returns 1
and it ends up calling build_perf_domains on write to 1 and
NOP when writing to 0. That is confusing and un-necessary.
Desired behavior would be to have this sysctl to enable/disable the EAS
on supported platform. On non-supported platform write to the sysctl
would return not supported error and read of the sysctl would return
empty. So sched_energy_aware returns empty - EAS is not possible at this moment
This will include EAS capable platforms which have at least one EAS
condition false during startup, e.g. not using the schedutil cpufreq governor
sched_energy_aware returns 0 - EAS is supported but disabled by admin.
sched_energy_aware returns 1 - EAS is supported and enabled.
User can find out the reason why EAS is not possible by checking
info messages. sched_is_eas_possible returns true if the platform
can do EAS at this moment.
Signed-off-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20231009060037.170765-3-sshegde@linux.vnet.ibm.com
Update_triggers() always returns now + group->rtpoll_min_period, and the
return value is only used by psi_rtpoll_work(), so change update_triggers()
to a void function, let group->rtpoll_next_update = now +
group->rtpoll_min_period directly.
This will avoid unnecessary function return value passing & simplifies
the function.
[ mingo: Updated changelog ]
Suggested-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/202310092024289721617@zte.com.cn
The Energy Aware Scheduler (EAS) estimates the energy consumption
of placing a task on different CPUs. The goal is to minimize this
energy consumption. Estimating the energy of different task placements
is increasingly complex with the size of the platform.
To avoid having a slow wake-up path, EAS is only enabled if this
complexity is low enough.
The current complexity limit was set in:
b68a4c0dba ("sched/topology: Disable EAS on inappropriate platforms")
... based on the first implementation of EAS, which was re-computing
the power of the whole platform for each task placement scenario, see:
390031e4c3 ("sched/fair: Introduce an energy estimation helper function")
... but the complexity of EAS was reduced in:
eb92692b25 ("sched/fair: Speed-up energy-aware wake-ups")
... and find_energy_efficient_cpu() (feec) algorithm was updated in:
3e8c6c9aac ("sched/fair: Remove task_util from effective utilization in feec()")
find_energy_efficient_cpu() (feec) is now doing:
feec()
\_ for_each_pd(pd) [0]
// get max_spare_cap_cpu and compute_prev_delta
\_ for_each_cpu(pd) [1]
\_ eenv_pd_busy_time(pd) [2]
\_ for_each_cpu(pd)
// compute_energy(pd) without the task
\_ eenv_pd_max_util(pd, -1) [3.0]
\_ for_each_cpu(pd)
\_ em_cpu_energy(pd, -1)
\_ for_each_ps(pd)
// compute_energy(pd) with the task on prev_cpu
\_ eenv_pd_max_util(pd, prev_cpu) [3.1]
\_ for_each_cpu(pd)
\_ em_cpu_energy(pd, prev_cpu)
\_ for_each_ps(pd)
// compute_energy(pd) with the task on max_spare_cap_cpu
\_ eenv_pd_max_util(pd, max_spare_cap_cpu) [3.2]
\_ for_each_cpu(pd)
\_ em_cpu_energy(pd, max_spare_cap_cpu)
\_ for_each_ps(pd)
[3.1] happens only once since prev_cpu is unique. With the same
definitions for nr_pd, nr_cpus and nr_ps, the complexity is of:
nr_pd * (2 * [nr_cpus in pd] + 2 * ([nr_cpus in pd] + [nr_ps in pd]))
+ ([nr_cpus in pd] + [nr_ps in pd])
[0] * ( [1] + [2] + [3.0] + [3.2] )
+ [3.1]
= nr_pd * (4 * [nr_cpus in pd] + 2 * [nr_ps in pd])
+ [nr_cpus in prev pd] + nr_ps
The complexity limit was set to 2048 in:
b68a4c0dba ("sched/topology: Disable EAS on inappropriate platforms")
... to make "EAS usable up to 16 CPUs with per-CPU DVFS and less than 8
performance states each". For the same platform, the complexity would
actually be of:
16 * (4 + 2 * 7) + 1 + 7 = 296
Since the EAS complexity was greatly reduced since the limit was
introduced, bigger platforms can handle EAS.
For instance, a platform with 112 CPUs with 7 performance states
each would not reach it:
112 * (4 + 2 * 7) + 1 + 7 = 2024
To reflect this improvement in the underlying EAS code, remove
the EAS complexity check.
Note that a limit on the number of CPUs still holds against
EM_MAX_NUM_CPUS to avoid overflows during the energy estimation.
[ mingo: Updates to the changelog. ]
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20231009060037.170765-2-sshegde@linux.vnet.ibm.com
Remove the rq::cpu_capacity_orig field and use arch_scale_cpu_capacity()
instead.
The scheduler uses 3 methods to get access to a CPU's max compute capacity:
- arch_scale_cpu_capacity(cpu) which is the default way to get a CPU's capacity.
- cpu_capacity_orig field which is periodically updated with
arch_scale_cpu_capacity().
- capacity_orig_of(cpu) which encapsulates rq->cpu_capacity_orig.
There is no real need to save the value returned by arch_scale_cpu_capacity()
in struct rq. arch_scale_cpu_capacity() returns:
- either a per_cpu variable.
- or a const value for systems which have only one capacity.
Remove rq::cpu_capacity_orig and use arch_scale_cpu_capacity() everywhere.
No functional changes.
Some performance tests on Arm64:
- small SMP device (hikey): no noticeable changes
- HMP device (RB5): hackbench shows minor improvement (1-2%)
- large smp (thx2): hackbench and tbench shows minor improvement (1%)
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20231009103621.374412-2-vincent.guittot@linaro.org
Doing this matches the natural type of 'int' based calculus
in sched_rt_handler(), and also enables the adding in of a
correct upper bounds check on the sysctl interface.
[ mingo: Rewrote the changelog. ]
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231008021538.3063250-1-yajun.deng@linux.dev
find_new_ilb() returns nr_cpu_ids on failure - which is the usual
cpumask bitops return pattern, but is weird & unnecessary in this
context: not only is it a global variable, it it is a +1 out of
bounds CPU index and also has different signedness ...
Its only user, kick_ilb(), then checks the return against nr_cpu_ids
to decide to return. There's no other use.
So instead of this, use a standard -1 return on failure to find an
idle CPU, as the argument is signed already.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Link: https://lore.kernel.org/r/20231006102518.2452758-4-mingo@kernel.org
The old pick_eevdf() could fail to find the actual earliest eligible
deadline when it descended to the right looking for min_deadline, but
it turned out that that min_deadline wasn't actually eligible. In that
case we need to go back and search through any left branches we
skipped looking for the actual best _eligible_ min_deadline.
This is more expensive, but still O(log n), and at worst should only
involve descending two branches of the rbtree.
I've run this through a userspace stress test (thank you
tools/lib/rbtree.c), so hopefully this implementation doesn't miss any
corner cases.
Fixes: 147f3efaa2 ("sched/fair: Implement an EEVDF-like scheduling policy")
Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/xm261qego72d.fsf_-_@google.com
Marek and Biju reported instances of:
"EEVDF scheduling fail, picking leftmost"
which Mike correlated with cgroup scheduling and the min_deadline heap
getting corrupted; some trace output confirms:
> And yeah, min_deadline is hosed somehow:
>
> validate_cfs_rq: --- /
> __print_se: ffff88845cf48080 w: 1024 ve: -58857638 lag: 870381 vd: -55861854 vmd: -66302085 E (11372/tr)
> __print_se: ffff88810d165800 w: 25 ve: -80323686 lag: 22336429 vd: -41496434 vmd: -66302085 E (-1//autogroup-31)
> __print_se: ffff888108379000 w: 25 ve: 0 lag: -57987257 vd: 114632828 vmd: 114632828 N (-1//autogroup-33)
> validate_cfs_rq: min_deadline: -55861854 avg_vruntime: -62278313462 / 1074 = -57987256
Turns out that reweight_entity(), which tries really hard to be fast,
does not do the normal dequeue+update+enqueue pattern but *does* scale
the deadline.
However, it then fails to propagate the updated deadline value up the
heap.
Fixes: 147f3efaa2 ("sched/fair: Implement an EEVDF-like scheduling policy")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reported-by: Biju Das <biju.das.jz@bp.renesas.com>
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Biju Das <biju.das.jz@bp.renesas.com>
Tested-by: Mike Galbraith <efault@gmx.de>
Link: https://lkml.kernel.org/r/20231006192445.GE743@noisy.programming.kicks-ass.net
Multiple blocked tasks are printed when the system hangs. They may have
the same parent pid, but belong to different task groups.
Printing tgid lets users better know whether these tasks are from the same
task group or not.
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230720080516.1515297-1-yajun.deng@linux.dev
The following commit:
9b3c4ab304 ("sched,rcu: Rework try_invoke_on_locked_down_task()")
... renamed try_invoke_on_locked_down_task() to task_call_func(),
but forgot to update the comment in try_to_wake_up().
But it turns out that the smp_rmb() doesn't live in task_call_func()
either, it was moved to __task_needs_rq_lock() in:
91dabf33ae ("sched: Fix race in task_call_func()")
Fix that now.
Also fix the s/smb/smp typo while at it.
Reported-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230731085759.11443-1-zhangqiao22@huawei.com
The Energy Aware Scheduler (EAS) relies on the schedutil governor.
When moving to/from the schedutil governor, sched domains must be
rebuilt to allow re-evaluating the enablement conditions of EAS.
This is done through sched_cpufreq_governor_change().
Having a cpufreq governor assumes a cpufreq driver is running.
Inserting/removing a cpufreq driver should trigger a re-evaluation
of EAS enablement conditions, avoiding to see EAS enabled when
removing a running cpufreq driver.
Rebuild the sched domains in schedutil's sugov_init()/sugov_exit(),
allowing to check EAS's enablement condition whenever schedutil
governor is initialized/exited from.
Move relevant code up in schedutil.c to avoid a split and conditional
function declaration.
Rename sched_cpufreq_governor_change() to sugov_eas_rebuild_sd().
Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The initialization code of the per-cpu sg_cpu struct is currently split
into two for-loop blocks. This can be simplified by merging the two
blocks into a single loop. This will make the code more maintainable.
Signed-off-by: Liao Chang <liaochang1@huawei.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When cpufreq's policy is 'single', there is a scenario that will
cause sg_policy's next_freq to be unable to update.
When the CPU's util is always max, the cpufreq will be max,
and then if we change the policy's scaling_max_freq to be a
lower freq, indeed, the sg_policy's next_freq need change to
be the lower freq, however, because the cpu_is_busy, the next_freq
would keep the max_freq.
For example:
The cpu7 is a single CPU:
unisoc:/sys/devices/system/cpu/cpufreq/policy7 # while true;do done& [1] 4737
unisoc:/sys/devices/system/cpu/cpufreq/policy7 # taskset -p 80 4737
pid 4737's current affinity mask: ff
pid 4737's new affinity mask: 80
unisoc:/sys/devices/system/cpu/cpufreq/policy7 # cat scaling_max_freq
2301000
unisoc:/sys/devices/system/cpu/cpufreq/policy7 # cat scaling_cur_freq
2301000
unisoc:/sys/devices/system/cpu/cpufreq/policy7 # echo 2171000 > scaling_max_freq
unisoc:/sys/devices/system/cpu/cpufreq/policy7 # cat scaling_max_freq
2171000
At this time, the sg_policy's next_freq would stay at 2301000, which
is wrong.
To fix this, add a check for the ->need_freq_update flag.
[ mingo: Clarified the changelog. ]
Co-developed-by: Guohua Yan <guohua.yan@unisoc.com>
Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Guohua Yan <guohua.yan@unisoc.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230719130527.8074-1-xuewen.yan@unisoc.com
The expectation is that placing a task at avg_vruntime() makes it
eligible. Turns out there is a corner case where this is not the case.
Specifically, avg_vruntime() relies on the fact that integer division
is a flooring function (eg. it discards the remainder). By this
property the value returned is slightly left of the true average.
However! when the average is a negative (relative to min_vruntime) the
effect is flipped and it becomes a ceil, with the result that the
returned value is just right of the average and thus not eligible.
Fixes: af4cf40470 ("sched/fair: Add cfs_rq::avg_vruntime")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tasks that never consume their full slice would not update their slice value.
This means that tasks that are spawned before the sysctl scaling keep their
original (UP) slice length.
Fixes: 147f3efaa2 ("sched/fair: Implement an EEVDF-like scheduling policy")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230915124822.847197830@noisy.programming.kicks-ass.net
The validation of the value written to sched_rt_period_us was broken
because:
- the sysclt_sched_rt_period is declared as unsigned int
- parsed by proc_do_intvec()
- the range is asserted after the value parsed by proc_do_intvec()
Because of this negative values written to the file were written into a
unsigned integer that were later on interpreted as large positive
integers which did passed the check:
if (sysclt_sched_rt_period <= 0)
return EINVAL;
This commit fixes the parsing by setting explicit range for both
perid_us and runtime_us into the sched_rt_sysctls table and processes
the values with proc_dointvec_minmax() instead.
Alternatively if we wanted to use full range of unsigned int for the
period value we would have to split the proc_handler and use
proc_douintvec() for it however even the
Documentation/scheduller/sched-rt-group.rst describes the range as 1 to
INT_MAX.
As far as I can tell the only problem this causes is that the sysctl
file allows writing negative values which when read back may confuse
userspace.
There is also a LTP test being submitted for these sysctl files at:
http://patchwork.ozlabs.org/project/ltp/patch/20230901144433.2526-1-chrubis@suse.cz/
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231002115553.3007-2-chrubis@suse.cz
It was useful to track feec() placement decision and debug the spare
capacity and optimization issues vs uclamp_max.
Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230916232955.2099394-4-qyousef@layalina.io
find_energy_efficient_cpu() bails out early if effective util of the
task is 0 as the delta at this point will be zero and there's nothing
for EAS to do. When uclamp is being used, this could lead to wrong
decisions when uclamp_max is set to 0. In this case the task is capped
to performance point 0, but it is actually running and consuming energy
and we can benefit from EAS energy calculations.
Rework the condition so that it bails out when both util and uclamp_min
are 0.
We can do that without needing to use uclamp_task_util(); remove it.
Fixes: d81304bc61 ("sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition")
Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230916232955.2099394-3-qyousef@layalina.io
When uclamp_max is being used, the util of the task could be higher than
the spare capacity of the CPU, but due to uclamp_max value we force-fit
it there.
The way the condition for checking for max_spare_cap in
find_energy_efficient_cpu() was constructed; it ignored any CPU that has
its spare_cap less than or _equal_ to max_spare_cap. Since we initialize
max_spare_cap to 0; this lead to never setting max_spare_cap_cpu and
hence ending up never performing compute_energy() for this cluster and
missing an opportunity for a better energy efficient placement to honour
uclamp_max setting.
max_spare_cap = 0;
cpu_cap = capacity_of(cpu) - cpu_util(p); // 0 if cpu_util(p) is high
...
util_fits_cpu(...); // will return true if uclamp_max forces it to fit
...
// this logic will fail to update max_spare_cap_cpu if cpu_cap is 0
if (cpu_cap > max_spare_cap) {
max_spare_cap = cpu_cap;
max_spare_cap_cpu = cpu;
}
prev_spare_cap suffers from a similar problem.
Fix the logic by converting the variables into long and treating -1
value as 'not populated' instead of 0 which is a viable and correct
spare capacity value. We need to be careful signed comparison is used
when comparing with cpu_cap in one of the conditions.
Fixes: 1d42509e47 ("sched/fair: Make EAS wakeup placement consider uclamp restrictions")
Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230916232955.2099394-2-qyousef@layalina.io
dl_rq->dl_nr_migratory is increased whenever a DL entity is enqueued and it has
nr_cpus_allowed > 1. Unlike the pushable_dl_tasks tree, dl_rq->dl_nr_migratory
includes a dl_rq's current task. This means a dl_rq can have a migratable
current, N non-migratable queued tasks, and be flagged as overloaded and have
its CPU set in the dlo_mask, despite having an empty pushable_tasks tree.
Make an dl_rq's overload logic be driven by {enqueue,dequeue}_pushable_dl_task(),
in other words make DL RQs only be flagged as overloaded if they have at
least one runnable-but-not-current migratable task.
o push_dl_task() is unaffected, as it is a no-op if there are no pushable
tasks.
o pull_dl_task() now no longer scans runqueues whose sole migratable task is
their current one, which it can't do anything about anyway.
It may also now pull tasks to a DL RQ with dl_nr_running > 1 if only its
current task is migratable.
Since dl_rq->dl_nr_migratory becomes unused, remove it.
RT had the exact same mechanism (rt_rq->rt_nr_migratory) which was dropped
in favour of relying on rt_rq->pushable_tasks, see:
612f769edd ("sched/rt: Make rt_rq->pushable_tasks updates drive rto_mask")
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20230928150251.463109-1-vschneid@redhat.com
During RCU-boost testing with the TREE03 rcutorture config, I found that
after a few hours, the machine locks up.
On tracing, I found that there is a live lock happening between 2 CPUs.
One CPU has an RT task running, while another CPU is being offlined
which also has an RT task running. During this offlining, all threads
are migrated. The migration thread is repeatedly scheduled to migrate
actively running tasks on the CPU being offlined. This results in a live
lock because select_fallback_rq() keeps picking the CPU that an RT task
is already running on only to get pushed back to the CPU being offlined.
It is anyway pointless to pick CPUs for pushing tasks to if they are
being offlined only to get migrated away to somewhere else. This could
also add unwanted latency to this task.
Fix these issues by not selecting CPUs in RT if they are not 'active'
for scheduling, using the cpu_active_mask. Other parts in core.c already
use cpu_active_mask to prevent tasks from being put on CPUs going
offline.
With this fix I ran the tests for days and could not reproduce the
hang. Without the patch, I hit it in a few hours.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230923011409.3522762-1-joel@joelfernandes.org
Sebastian noted that the rto_push_work IRQ work can be queued for a CPU
that has an empty pushable_tasks list, which means nothing useful will be
done in the IPI other than queue the work for the next CPU on the rto_mask.
rto_push_irq_work_func() only operates on tasks in the pushable_tasks list,
but the conditions for that irq_work to be queued (and for a CPU to be
added to the rto_mask) rely on rq_rt->nr_migratory instead.
nr_migratory is increased whenever an RT task entity is enqueued and it has
nr_cpus_allowed > 1. Unlike the pushable_tasks list, nr_migratory includes a
rt_rq's current task. This means a rt_rq can have a migratible current, N
non-migratible queued tasks, and be flagged as overloaded / have its CPU
set in the rto_mask, despite having an empty pushable_tasks list.
Make an rt_rq's overload logic be driven by {enqueue,dequeue}_pushable_task().
Since rt_rq->{rt_nr_migratory,rt_nr_total} become unused, remove them.
Note that the case where the current task is pushed away to make way for a
migration-disabled task remains unchanged: the migration-disabled task has
to be in the pushable_tasks list in the first place, which means it has
nr_cpus_allowed > 1.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20230811112044.3302588-1-vschneid@redhat.com
Simplify the conditional logic for checking worker flags
by splitting the original compound `if` statement into
separate `if` and `else if` clauses.
This modification not only retains the previous functionality,
but also reduces a single `if` check, improving code clarity
and potentially enhancing performance.
Signed-off-by: Wang Jinchao <wangjinchao@xfusion.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/ZOIMvURE99ZRAYEj@fedora
We've observed the following warning being hit in
distribute_cfs_runtime():
SCHED_WARN_ON(cfs_rq->runtime_remaining > 0)
We have the following race:
- CPU 0: running bandwidth distribution (distribute_cfs_runtime).
Inspects the local cfs_rq and makes its runtime_remaining positive.
However, we defer unthrottling the local cfs_rq until after
considering all remote cfs_rq's.
- CPU 1: starts running bandwidth distribution from the slack timer. When
it finds the cfs_rq for CPU 0 on the throttled list, it observers the
that the cfs_rq is throttled, yet is not on the CSD list, and has a
positive runtime_remaining, thus triggering the warning in
distribute_cfs_runtime.
To fix this, we can rework the local unthrottling logic to put the local
cfs_rq on a local list, so that any future bandwidth distributions will
realize that the cfs_rq is about to be unthrottled.
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230922230535.296350-2-joshdon@google.com
This makes the following patch cleaner by avoiding extra CONFIG_SMP
conditionals on the availability of rq->throttled_csd_list.
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230922230535.296350-1-joshdon@google.com
in_atomic_preempt_off() already gets called in schedule_debug() once,
which is the only caller of __schedule_bug().
Skip the second call within __schedule_bug(), it should always be true
at this point.
[ mingo: Clarified the changelog. ]
Signed-off-by: Liming Wu <liming.wu@jaguarmicro.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230825023501.1848-1-liming.wu@jaguarmicro.com
Since commit:
8a99b6833c ("sched: Move SCHED_DEBUG sysctl to debugfs")
The sched_debug interface moved from /proc to debugfs. The comment
mentions still the outdated proc interfaces.
Update the comment, point to the current location of the interface.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230920130025.412071-3-bigeasy@linutronix.de
With PREEMPT_RT there is a rt_mutex recursion problem where
sched_submit_work() can use an rtlock (aka spinlock_t). More
specifically what happens is:
mutex_lock() /* really rt_mutex */
...
__rt_mutex_slowlock_locked()
task_blocks_on_rt_mutex()
// enqueue current task as waiter
// do PI chain walk
rt_mutex_slowlock_block()
schedule()
sched_submit_work()
...
spin_lock() /* really rtlock */
...
__rt_mutex_slowlock_locked()
task_blocks_on_rt_mutex()
// enqueue current task as waiter *AGAIN*
// *CONFUSION*
Fix this by making rt_mutex do the sched_submit_work() early, before
it enqueues itself as a waiter -- before it even knows *if* it will
wait.
[[ basically Thomas' patch but with different naming and a few asserts
added ]]
Originally-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230908162254.999499-5-bigeasy@linutronix.de
There are currently two implementations of this basic __schedule()
loop, and there is soon to be a third.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230908162254.999499-4-bigeasy@linutronix.de
Even though sched_submit_work() is ran from preemptible context,
it is discouraged to have it use blocking locks due to the recursion
potential.
Enforce this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230908162254.999499-2-bigeasy@linutronix.de
Initial booting is setting the task flag to idle (PF_IDLE) by the call
path sched_init() -> init_idle(). Having the task idle and calling
call_rcu() in kernel/rcu/tiny.c means that TIF_NEED_RESCHED will be
set. Subsequent calls to any cond_resched() will enable IRQs,
potentially earlier than the IRQ setup has completed. Recent changes
have caused just this scenario and IRQs have been enabled early.
This causes a warning later in start_kernel() as interrupts are enabled
before they are fully set up.
Fix this issue by setting the PF_IDLE flag later in the boot sequence.
Although the boot task was marked as idle since (at least) d80e4fda576d,
I am not sure that it is wrong to do so. The forced context-switch on
idle task was introduced in the tiny_rcu update, so I'm going to claim
this fixes 5f6130fa52.
Fixes: 5f6130fa52 ("tiny_rcu: Directly force QS when call_rcu_[bh|sched]() on idle_task")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-mm/CAMuHMdWpvpWoDa=Ox-do92czYRvkok6_x6pYUH+ZouMcJbXy+Q@mail.gmail.com/
The name is a bit opaque - make it clear that this is about wakeup
preemption.
Also rename the ->check_preempt_curr() methods similarly.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Other scheduling classes already postfix their similar methods
with the class name.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Remove duplicated includes of linux/cgroup.h and linux/psi.h. Both of
these includes are included regardless of the config and they are all
protected by ifndef, so no point including them again.
Signed-off-by: GUO Zihua <guozihua@huawei.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230818015633.18370-1-guozihua@huawei.com
When using sysbench to benchmark Postgres in a single docker instance
with sysbench's nr_threads set to nr_cpu, it is observed there are times
update_cfs_group() and update_load_avg() shows noticeable overhead on
a 2sockets/112core/224cpu Intel Sapphire Rapids(SPR):
13.75% 13.74% [kernel.vmlinux] [k] update_cfs_group
10.63% 10.04% [kernel.vmlinux] [k] update_load_avg
Annotate shows the cycles are mostly spent on accessing tg->load_avg
with update_load_avg() being the write side and update_cfs_group() being
the read side. tg->load_avg is per task group and when different tasks
of the same taskgroup running on different CPUs frequently access
tg->load_avg, it can be heavily contended.
E.g. when running postgres_sysbench on a 2sockets/112cores/224cpus Intel
Sappire Rapids, during a 5s window, the wakeup number is 14millions and
migration number is 11millions and with each migration, the task's load
will transfer from src cfs_rq to target cfs_rq and each change involves
an update to tg->load_avg. Since the workload can trigger as many wakeups
and migrations, the access(both read and write) to tg->load_avg can be
unbound. As a result, the two mentioned functions showed noticeable
overhead. With netperf/nr_client=nr_cpu/UDP_RR, the problem is worse:
during a 5s window, wakeup number is 21millions and migration number is
14millions; update_cfs_group() costs ~25% and update_load_avg() costs ~16%.
Reduce the overhead by limiting updates to tg->load_avg to at most once
per ms. The update frequency is a tradeoff between tracking accuracy and
overhead. 1ms is chosen because PELT window is roughly 1ms and it
delivered good results for the tests that I've done. After this change,
the cost of accessing tg->load_avg is greatly reduced and performance
improved. Detailed test results below.
==============================
postgres_sysbench on SPR:
25%
base: 42382±19.8%
patch: 50174±9.5% (noise)
50%
base: 67626±1.3%
patch: 67365±3.1% (noise)
75%
base: 100216±1.2%
patch: 112470±0.1% +12.2%
100%
base: 93671±0.4%
patch: 113563±0.2% +21.2%
==============================
hackbench on ICL:
group=1
base: 114912±5.2%
patch: 117857±2.5% (noise)
group=4
base: 359902±1.6%
patch: 361685±2.7% (noise)
group=8
base: 461070±0.8%
patch: 491713±0.3% +6.6%
group=16
base: 309032±5.0%
patch: 378337±1.3% +22.4%
=============================
hackbench on SPR:
group=1
base: 100768±2.9%
patch: 103134±2.9% (noise)
group=4
base: 413830±12.5%
patch: 378660±16.6% (noise)
group=8
base: 436124±0.6%
patch: 490787±3.2% +12.5%
group=16
base: 457730±3.2%
patch: 680452±1.3% +48.8%
============================
netperf/udp_rr on ICL
25%
base: 114413±0.1%
patch: 115111±0.0% +0.6%
50%
base: 86803±0.5%
patch: 86611±0.0% (noise)
75%
base: 35959±5.3%
patch: 49801±0.6% +38.5%
100%
base: 61951±6.4%
patch: 70224±0.8% +13.4%
===========================
netperf/udp_rr on SPR
25%
base: 104954±1.3%
patch: 107312±2.8% (noise)
50%
base: 55394±4.6%
patch: 54940±7.4% (noise)
75%
base: 13779±3.1%
patch: 36105±1.1% +162%
100%
base: 9703±3.7%
patch: 28011±0.2% +189%
==============================================
netperf/tcp_stream on ICL (all in noise range)
25%
base: 43092±0.1%
patch: 42891±0.5%
50%
base: 19278±14.9%
patch: 22369±7.2%
75%
base: 16822±3.0%
patch: 17086±2.3%
100%
base: 18216±0.6%
patch: 18078±2.9%
===============================================
netperf/tcp_stream on SPR (all in noise range)
25%
base: 34491±0.3%
patch: 34886±0.5%
50%
base: 19278±14.9%
patch: 22369±7.2%
75%
base: 16822±3.0%
patch: 17086±2.3%
100%
base: 18216±0.6%
patch: 18078±2.9%
Reported-by: Nitin Tekchandani <nitin.tekchandani@intel.com>
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: David Vernet <void@manifault.com>
Tested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Tested-by: Swapnil Sapkal <Swapnil.Sapkal@amd.com>
Link: https://lkml.kernel.org/r/20230912065808.2530-2-aaron.lu@intel.com
After commit f5d39b0208 ("freezer,sched: Rewrite core freezer logic"),
tasks that transition directly from TASK_FREEZABLE to TASK_FROZEN are
always woken up on the thaw path. Prior to that commit, tasks could ask
freezer to consider them "frozen enough" via freezer_do_not_count(). The
commit replaced freezer_do_not_count() with a TASK_FREEZABLE state which
allows freezer to immediately mark the task as TASK_FROZEN without
waking up the task. This is efficient for the suspend path, but on the
thaw path, the task is always woken up even if the task didn't need to
wake up and goes back to its TASK_(UN)INTERRUPTIBLE state. Although
these tasks are capable of handling of the wakeup, we can observe a
power/perf impact from the extra wakeup.
We observed on Android many tasks wait in the TASK_FREEZABLE state
(particularly due to many of them being binder clients). We observed
nearly 4x the number of tasks and a corresponding linear increase in
latency and power consumption when thawing the system. The latency
increased from ~15ms to ~50ms.
Avoid the spurious wakeups by saving the state of TASK_FREEZABLE tasks.
If the task was running before entering TASK_FROZEN state
(__refrigerator()) or if the task received a wake up for the saved
state, then the task is woken on thaw. saved_state from PREEMPT_RT locks
can be re-used because freezer would not stomp on the rtlock wait flow:
TASK_RTLOCK_WAIT isn't considered freezable.
Reported-by: Prakash Viswalingam <quic_prakashv@quicinc.com>
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation for freezer to also use saved_state, remove the
CONFIG_PREEMPT_RT compilation guard around saved_state.
On the arm64 platform I tested which did not have CONFIG_PREEMPT_RT,
there was no statistically significant deviation by applying this patch.
Test methodology:
perf bench sched message -g 40 -l 40
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We don't need to maintain per-queue leaf_cfs_rq_list on !SMP, since
it's used for cfs_rq load tracking & balancing on SMP.
But sched debug interface uses it to print per-cfs_rq stats.
This patch fixes the !SMP version of cfs_rq_is_decayed(), so the
per-queue leaf_cfs_rq_list is also maintained correctly on !SMP,
to fix the warning in assert_list_leaf_cfs_rq().
Fixes: 0a00a35464 ("sched/fair: Delete useless condition in tg_unthrottle_up()")
Reported-by: Leo Yu-Chi Liang <ycliang@andestech.com>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Leo Yu-Chi Liang <ycliang@andestech.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Closes: https://lore.kernel.org/all/ZN87UsqkWcFLDxea@swlinux02/
Link: https://lore.kernel.org/r/20230913132031.2242151-1-chengming.zhou@linux.dev
sched_numa_find_nth_cpu() doesn't handle NUMA_NO_NODE properly, and
may crash kernel if passed with it. On the other hand, the only user
of sched_numa_find_nth_cpu() has to check NUMA_NO_NODE case explicitly.
It would be easier for users if this logic will get moved into
sched_numa_find_nth_cpu().
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20230819141239.287290-6-yury.norov@gmail.com
task_numa_placement() searches for a nearest node to migrate by calling
for_each_node_state(). Now that we have numa_nearest_node(), switch to
using it.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20230819141239.287290-3-yury.norov@gmail.com
For SMT4, any group with more than 2 tasks will be marked as
group_smt_balance. Retain the behaviour of group_has_spare by marking
the busiest group as the group which has the least number of idle_cpus.
Also, handle rounding effect of adding (ncores_local + ncores_busy) when
the local is fully idle and busy group imbalance is less than 2 tasks.
Local group should try to pull at least 1 task in this case so imbalance
should be set to 2 instead.
Fixes: fee1759e4f ("sched/fair: Determine active load balance for SMT sched groups")
Acked-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/6cd1633036bb6b651af575c32c2a9608a106702c.camel@linux.intel.com
Use guards to reduce gotos and simplify control flow.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use guards to reduce gotos and simplify control flow.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use guards to reduce gotos and simplify control flow.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use guards to reduce gotos and simplify control flow.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use guards to reduce gotos and simplify control flow.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use guards to reduce gotos and simplify control flow.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use guards to reduce gotos and simplify control flow.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The Itanium architecture is obsolete, and an informal survey [0] reveals
that any residual use of Itanium hardware in production is mostly HP-UX
or OpenVMS based. The use of Linux on Itanium appears to be limited to
enthusiasts that occasionally boot a fresh Linux kernel to see whether
things are still working as intended, and perhaps to churn out some
distro packages that are rarely used in practice.
None of the original companies behind Itanium still produce or support
any hardware or software for the architecture, and it is listed as
'Orphaned' in the MAINTAINERS file, as apparently, none of the engineers
that contributed on behalf of those companies (nor anyone else, for that
matter) have been willing to support or maintain the architecture
upstream or even be responsible for applying the odd fix. The Intel
firmware team removed all IA-64 support from the Tianocore/EDK2
reference implementation of EFI in 2018. (Itanium is the original
architecture for which EFI was developed, and the way Linux supports it
deviates significantly from other architectures.) Some distros, such as
Debian and Gentoo, still maintain [unofficial] ia64 ports, but many have
dropped support years ago.
While the argument is being made [1] that there is a 'for the common
good' angle to being able to build and run existing projects such as the
Grid Community Toolkit [2] on Itanium for interoperability testing, the
fact remains that none of those projects are known to be deployed on
Linux/ia64, and very few people actually have access to such a system in
the first place. Even if there were ways imaginable in which Linux/ia64
could be put to good use today, what matters is whether anyone is
actually doing that, and this does not appear to be the case.
There are no emulators widely available, and so boot testing Itanium is
generally infeasible for ordinary contributors. GCC still supports IA-64
but its compile farm [3] no longer has any IA-64 machines. GLIBC would
like to get rid of IA-64 [4] too because it would permit some overdue
code cleanups. In summary, the benefits to the ecosystem of having IA-64
be part of it are mostly theoretical, whereas the maintenance overhead
of keeping it supported is real.
So let's rip off the band aid, and remove the IA-64 arch code entirely.
This follows the timeline proposed by the Debian/ia64 maintainer [5],
which removes support in a controlled manner, leaving IA-64 in a known
good state in the most recent LTS release. Other projects will follow
once the kernel support is removed.
[0] https://lore.kernel.org/all/CAMj1kXFCMh_578jniKpUtx_j8ByHnt=s7S+yQ+vGbKt9ud7+kQ@mail.gmail.com/
[1] https://lore.kernel.org/all/0075883c-7c51-00f5-2c2d-5119c1820410@web.de/
[2] https://gridcf.org/gct-docs/latest/index.html
[3] https://cfarm.tetaneutral.net/machines/list/
[4] https://lore.kernel.org/all/87bkiilpc4.fsf@mid.deneb.enyo.de/
[5] https://lore.kernel.org/all/ff58a3e76e5102c94bb5946d99187b358def688a.camel@physik.fu-berlin.de/
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
should_we_balance() is called in load_balance() to find out if the CPU that
is trying to do the load balance is the right one or not.
With commit:
b1bfeab9b002("sched/fair: Consider the idle state of the whole core for load balance")
the code tries to find an idle core to do the load balancing
and falls back on an idle sibling CPU if there is no idle core.
However, on larger SMT systems, it could be needlessly iterating to find a
idle by scanning all the CPUs in an non-idle core. If the core is not idle,
and first SMT sibling which is idle has been found, then its not needed to
check other SMT siblings for idleness
Lets say in SMT4, Core0 has 0,2,4,6 and CPU0 is BUSY and rest are IDLE.
balancing domain is MC/DIE. CPU2 will be set as the first idle_smt and
same process would be repeated for CPU4 and CPU6 but this is unnecessary.
Since calling is_core_idle loops through all CPU's in the SMT mask, effect
is multiplied by weight of smt_mask. For example,when say 1 CPU is busy,
we would skip loop for 2 CPU's and skip iterating over 8CPU's. That
effect would be more in DIE/NUMA domain where there are more cores.
Testing and performance evaluation
==================================
The test has been done on this system which has 12 cores, i.e 24 small
cores with SMT=4:
lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 96
On-line CPU(s) list: 0-95
Model name: POWER10 (architected), altivec supported
Thread(s) per core: 8
Used funclatency bcc tool to evaluate the time taken by should_we_balance(). For
base tip/sched/core the time taken is collected by making the
should_we_balance() noinline. time is in nanoseconds. The values are
collected by running the funclatency tracer for 60 seconds. values are
average of 3 such runs. This represents the expected reduced time with
patch.
tip/sched/core was at commit:
2f88c8e802 ("sched/eevdf/doc: Modify the documented knob to base_slice_ns as well")
Results:
------------------------------------------------------------------------------
workload tip/sched/core with_patch(%gain)
------------------------------------------------------------------------------
idle system 809.3 695.0(16.45)
stress ng – 12 threads -l 100 1013.5 893.1(13.49)
stress ng – 24 threads -l 100 1073.5 980.0(9.54)
stress ng – 48 threads -l 100 683.0 641.0(6.55)
stress ng – 96 threads -l 100 2421.0 2300(5.26)
stress ng – 96 threads -l 15 375.5 377.5(-0.53)
stress ng – 96 threads -l 25 635.5 637.5(-0.31)
stress ng – 96 threads -l 35 934.0 891.0(4.83)
Ran schbench(old), hackbench and stress_ng to evaluate the workload
performance between tip/sched/core and with patch.
No modification to tip/sched/core
TL;DR:
Good improvement is seen with schbench. when hackbench and stress_ng
runs for longer good improvement is seen.
------------------------------------------------------------------------------
schbench(old) tip +patch(%gain)
10 iterations sched/core
------------------------------------------------------------------------------
1 Threads
50.0th: 8.00 9.00(-12.50)
75.0th: 9.60 9.00(6.25)
90.0th: 11.80 10.20(13.56)
95.0th: 12.60 10.40(17.46)
99.0th: 13.60 11.90(12.50)
99.5th: 14.10 12.60(10.64)
99.9th: 15.90 14.60(8.18)
2 Threads
50.0th: 9.90 9.20(7.07)
75.0th: 12.60 10.10(19.84)
90.0th: 15.50 12.00(22.58)
95.0th: 17.70 14.00(20.90)
99.0th: 21.20 16.90(20.28)
99.5th: 22.60 17.50(22.57)
99.9th: 30.40 19.40(36.18)
4 Threads
50.0th: 12.50 10.60(15.20)
75.0th: 15.30 12.00(21.57)
90.0th: 18.60 14.10(24.19)
95.0th: 21.30 16.20(23.94)
99.0th: 26.00 20.70(20.38)
99.5th: 27.60 22.50(18.48)
99.9th: 33.90 31.40(7.37)
8 Threads
50.0th: 16.30 14.30(12.27)
75.0th: 20.20 17.40(13.86)
90.0th: 24.50 21.90(10.61)
95.0th: 27.30 24.70(9.52)
99.0th: 35.00 31.20(10.86)
99.5th: 46.40 33.30(28.23)
99.9th: 89.30 57.50(35.61)
16 Threads
50.0th: 22.70 20.70(8.81)
75.0th: 30.10 27.40(8.97)
90.0th: 36.00 32.80(8.89)
95.0th: 39.60 36.40(8.08)
99.0th: 49.20 44.10(10.37)
99.5th: 64.90 50.50(22.19)
99.9th: 143.50 100.60(29.90)
32 Threads
50.0th: 34.60 35.50(-2.60)
75.0th: 48.20 50.50(-4.77)
90.0th: 59.20 62.40(-5.41)
95.0th: 65.20 69.00(-5.83)
99.0th: 80.40 83.80(-4.23)
99.5th: 102.10 98.90(3.13)
99.9th: 727.10 506.80(30.30)
schbench does improve in general. There is some run to run variation with
schbench. Did a validation run to confirm that trend is similar.
------------------------------------------------------------------------------
hackbench tip +patch(%gain)
20 iterations, 50000 loops sched/core
------------------------------------------------------------------------------
Process 10 groups : 11.74 11.70(0.34)
Process 20 groups : 22.73 22.69(0.18)
Process 30 groups : 33.39 33.40(-0.03)
Process 40 groups : 43.73 43.61(0.27)
Process 50 groups : 53.82 54.35(-0.98)
Process 60 groups : 64.16 65.29(-1.76)
thread 10 Time : 12.81 12.79(0.16)
thread 20 Time : 24.63 24.47(0.65)
Process(Pipe) 10 Time : 6.40 6.34(0.94)
Process(Pipe) 20 Time : 10.62 10.63(-0.09)
Process(Pipe) 30 Time : 15.09 14.84(1.66)
Process(Pipe) 40 Time : 19.42 19.01(2.11)
Process(Pipe) 50 Time : 24.04 23.34(2.91)
Process(Pipe) 60 Time : 28.94 27.51(4.94)
thread(Pipe) 10 Time : 6.96 6.87(1.29)
thread(Pipe) 20 Time : 11.74 11.73(0.09)
hackbench shows slight improvement with pipe. Slight degradation in process.
------------------------------------------------------------------------------
stress_ng tip +patch(%gain)
10 iterations 100000 cpu_ops sched/core
------------------------------------------------------------------------------
--cpu=96 -util=100 Time taken : 5.30, 5.01(5.47)
--cpu=48 -util=100 Time taken : 7.94, 6.73(15.24)
--cpu=24 -util=100 Time taken : 11.67, 8.75(25.02)
--cpu=12 -util=100 Time taken : 15.71, 15.02(4.39)
--cpu=96 -util=10 Time taken : 22.71, 22.19(2.29)
--cpu=96 -util=20 Time taken : 12.14, 12.37(-1.89)
--cpu=96 -util=30 Time taken : 8.76, 8.86(-1.14)
--cpu=96 -util=40 Time taken : 7.13, 7.14(-0.14)
--cpu=96 -util=50 Time taken : 6.10, 6.13(-0.49)
--cpu=96 -util=60 Time taken : 5.42, 5.41(0.18)
--cpu=96 -util=70 Time taken : 4.94, 4.94(0.00)
--cpu=96 -util=80 Time taken : 4.56, 4.53(0.66)
--cpu=96 -util=90 Time taken : 4.27, 4.26(0.23)
Good improvement seen with 24 CPUs. In this case only one CPU is busy,
and no core is idle. Decent improvement with 100% utilization case. no
difference in other utilization.
Fixes: b1bfeab9b0 ("sched/fair: Consider the idle state of the whole core for load balance")
Signed-off-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230902081204.232218-1-sshegde@linux.vnet.ibm.com
The following commit deserves special mention:
22dc02f81c Revert "sched/fair: Move unused stub functions to header"
This is in x86/cleanups, because the revert is a re-application of a
number of cleanups that got removed inadvertedly.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-cleanups-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 cleanups from Ingo Molnar:
"The following commit deserves special mention:
22dc02f81c Revert "sched/fair: Move unused stub functions to header"
This is in x86/cleanups, because the revert is a re-application of a
number of cleanups that got removed inadvertedly"
[ This also effectively undoes the amd_check_microcode() microcode
declaration change I had done in my microcode loader merge in commit
42a7f6e3ff ("Merge tag 'x86_microcode_for_v6.6_rc1' [...]").
I picked the declaration change by Arnd from this branch instead,
which put it in <asm/processor.h> instead of <asm/microcode.h> like I
had done in my merge resolution - Linus ]
* tag 'x86-cleanups-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/platform/uv: Refactor code using deprecated strncpy() interface to use strscpy()
x86/hpet: Refactor code using deprecated strncpy() interface to use strscpy()
x86/platform/uv: Refactor code using deprecated strcpy()/strncpy() interfaces to use strscpy()
x86/qspinlock-paravirt: Fix missing-prototype warning
x86/paravirt: Silence unused native_pv_lock_init() function warning
x86/alternative: Add a __alt_reloc_selftest() prototype
x86/purgatory: Include header for warn() declaration
x86/asm: Avoid unneeded __div64_32 function definition
Revert "sched/fair: Move unused stub functions to header"
x86/apic: Hide unused safe_smp_processor_id() on 32-bit UP
x86/cpu: Fix amd_check_microcode() declaration
- The biggest change is introduction of a new iteration of the
SCHED_FAIR interactivity code: the EEVDF ("Earliest Eligible Virtual
Deadline First") scheduler.
EEVDF too is a virtual-time scheduler, with two parameters (weight
and relative deadline), compared to CFS that had weight only.
It completely reworks the base scheduler: placement, preemption,
picking -- everything.
LWN.net, as usual, has a terrific writeup about EEVDF:
https://lwn.net/Articles/925371/
Preemption (both tick and wakeup) is driven by testing against
a fresh pick. Because the tree is now effectively an interval
tree, and the selection is no longer the 'leftmost' task,
over-scheduling is less of a problem. A lot of the CFS
heuristics are removed or replaced by more natural latency-space
parameters & constructs.
In terms of expected performance regressions: we'll and can fix
everything where a 'good' workload misbehaves with the new scheduler,
but EEVDF inevitably changes workload scheduling in a binary fashion,
hopefully for the better in the overwhelming majority of cases,
but in some cases it won't, especially in adversarial loads that
got lucky with the previous code, such as some variants of hackbench.
We are trying hard to err on the side of fixing all performance
regressions, but we expect some inevitable post-release iterations
of that process.
- Improve load-balancing on hybrid x86 systems: enable cluster
scheduling (again).
- Improve & fix bandwidth-scheduling on nohz systems.
- Improve bandwidth-throttling.
- Use lock guards to simplify and de-goto-ify control flow.
- Misc improvements, cleanups and fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- The biggest change is introduction of a new iteration of the
SCHED_FAIR interactivity code: the EEVDF ("Earliest Eligible Virtual
Deadline First") scheduler
EEVDF too is a virtual-time scheduler, with two parameters (weight
and relative deadline), compared to CFS that had weight only. It
completely reworks the base scheduler: placement, preemption, picking
-- everything
LWN.net, as usual, has a terrific writeup about EEVDF:
https://lwn.net/Articles/925371/
Preemption (both tick and wakeup) is driven by testing against a
fresh pick. Because the tree is now effectively an interval tree, and
the selection is no longer the 'leftmost' task, over-scheduling is
less of a problem. A lot of the CFS heuristics are removed or
replaced by more natural latency-space parameters & constructs
In terms of expected performance regressions: we will and can fix
everything where a 'good' workload misbehaves with the new scheduler,
but EEVDF inevitably changes workload scheduling in a binary fashion,
hopefully for the better in the overwhelming majority of cases, but
in some cases it won't, especially in adversarial loads that got
lucky with the previous code, such as some variants of hackbench. We
are trying hard to err on the side of fixing all performance
regressions, but we expect some inevitable post-release iterations of
that process
- Improve load-balancing on hybrid x86 systems: enable cluster
scheduling (again)
- Improve & fix bandwidth-scheduling on nohz systems
- Improve bandwidth-throttling
- Use lock guards to simplify and de-goto-ify control flow
- Misc improvements, cleanups and fixes
* tag 'sched-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
sched/eevdf/doc: Modify the documented knob to base_slice_ns as well
sched/eevdf: Curb wakeup-preemption
sched: Simplify sched_core_cpu_{starting,deactivate}()
sched: Simplify try_steal_cookie()
sched: Simplify sched_tick_remote()
sched: Simplify sched_exec()
sched: Simplify ttwu()
sched: Simplify wake_up_if_idle()
sched: Simplify: migrate_swap_stop()
sched: Simplify sysctl_sched_uclamp_handler()
sched: Simplify get_nohz_timer_target()
sched/rt: sysctl_sched_rr_timeslice show default timeslice after reset
sched/rt: Fix sysctl_sched_rr_timeslice intial value
sched/fair: Block nohz tick_stop when cfs bandwidth in use
sched, cgroup: Restore meaning to hierarchical_quota
MAINTAINERS: Add Peter explicitly to the psi section
sched/psi: Select KERNFS as needed
sched/topology: Align group flags when removing degenerate domain
sched/fair: remove util_est boosting
sched/fair: Propagate enqueue flags into place_entity()
...
Mike and others noticed that EEVDF does like to over-schedule quite a
bit -- which does hurt performance of a number of benchmarks /
workloads.
In particular, what seems to cause over-scheduling is that when lag is
of the same order (or larger) than the request / slice then placement
will not only cause the task to be placed left of current, but also
with a smaller deadline than current, which causes immediate
preemption.
[ notably, lag bounds are relative to HZ ]
Mike suggested we stick to picking 'current' for as long as it's
eligible to run, giving it uninterrupted runtime until it reaches
parity with the pack.
Augment Mike's suggestion by only allowing it to exhaust it's initial
request.
One random data point:
echo NO_RUN_TO_PARITY > /debug/sched/features
perf stat -a -e context-switches --repeat 10 -- perf bench sched messaging -g 20 -t -l 5000
3,723,554 context-switches ( +- 0.56% )
9.5136 +- 0.0394 seconds time elapsed ( +- 0.41% )
echo RUN_TO_PARITY > /debug/sched/features
perf stat -a -e context-switches --repeat 10 -- perf bench sched messaging -g 20 -t -l 5000
2,556,535 context-switches ( +- 0.51% )
9.2427 +- 0.0302 seconds time elapsed ( +- 0.33% )
Suggested-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230816134059.GC982867@hirez.programming.kicks-ass.net
Use guards to reduce gotos and simplify control flow.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20230801211811.828443100@infradead.org
The sched_rr_timeslice can be reset to default by writing value that is
<= 0. However after reading from this file we always got the last value
written, which is not useful at all.
$ echo -1 > /proc/sys/kernel/sched_rr_timeslice_ms
$ cat /proc/sys/kernel/sched_rr_timeslice_ms
-1
Fix this by setting the variable that holds the sysctl file value to the
jiffies_to_msecs(RR_TIMESLICE) in case that <= 0 value was written.
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Tested-by: Petr Vorel <pvorel@suse.cz>
Link: https://lore.kernel.org/r/20230802151906.25258-3-chrubis@suse.cz
There is a 10% rounding error in the intial value of the
sysctl_sched_rr_timeslice with CONFIG_HZ_300=y.
This was found with LTP test sched_rr_get_interval01:
sched_rr_get_interval01.c:57: TPASS: sched_rr_get_interval() passed
sched_rr_get_interval01.c:64: TPASS: Time quantum 0s 99999990ns
sched_rr_get_interval01.c:72: TFAIL: /proc/sys/kernel/sched_rr_timeslice_ms != 100 got 90
sched_rr_get_interval01.c:57: TPASS: sched_rr_get_interval() passed
sched_rr_get_interval01.c:64: TPASS: Time quantum 0s 99999990ns
sched_rr_get_interval01.c:72: TFAIL: /proc/sys/kernel/sched_rr_timeslice_ms != 100 got 90
What this test does is to compare the return value from the
sched_rr_get_interval() and the sched_rr_timeslice_ms sysctl file and
fails if they do not match.
The problem it found is the intial sysctl file value which was computed as:
static int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
which works fine as long as MSEC_PER_SEC is multiple of HZ, however it
introduces 10% rounding error for CONFIG_HZ_300:
(MSEC_PER_SEC / HZ) * (100 * HZ / 1000)
(1000 / 300) * (100 * 300 / 1000)
3 * 30 = 90
This can be easily fixed by reversing the order of the multiplication
and division. After this fix we get:
(MSEC_PER_SEC * (100 * HZ / 1000)) / HZ
(1000 * (100 * 300 / 1000)) / 300
(1000 * 30) / 300 = 100
Fixes: 975e155ed8 ("sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds")
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Petr Vorel <pvorel@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Tested-by: Petr Vorel <pvorel@suse.cz>
Link: https://lore.kernel.org/r/20230802151906.25258-2-chrubis@suse.cz
Pick up the EEVDF work into the main branch - it's looking good so far.
Conflicts:
kernel/sched/features.h
Signed-off-by: Ingo Molnar <mingo@kernel.org>
CFS bandwidth limits and NOHZ full don't play well together. Tasks
can easily run well past their quotas before a remote tick does
accounting. This leads to long, multi-period stalls before such
tasks can run again. Currently, when presented with these conflicting
requirements the scheduler is favoring nohz_full and letting the tick
be stopped. However, nohz tick stopping is already best-effort, there
are a number of conditions that can prevent it, whereas cfs runtime
bandwidth is expected to be enforced.
Make the scheduler favor bandwidth over stopping the tick by setting
TICK_DEP_BIT_SCHED when the only running task is a cfs task with
runtime limit enabled. We use cfs_b->hierarchical_quota to
determine if the task requires the tick.
Add check in pick_next_task_fair() as well since that is where
we have a handle on the task that is actually going to be running.
Add check in sched_can_stop_tick() to cover some edge cases such
as nr_running going from 2->1 and the 1 remains the running task.
Reviewed-By: Ben Segall <bsegall@google.com>
Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230712133357.381137-3-pauld@redhat.com
In cgroupv2 cfs_b->hierarchical_quota is set to -1 for all task
groups due to the previous fix simply taking the min. It should
reflect a limit imposed at that level or by an ancestor. Even
though cgroupv2 does not require child quota to be less than or
equal to that of its ancestors the task group will still be
constrained by such a quota so this should be shown here. Cgroupv1
continues to set this correctly.
In both cases, add initialization when a new task group is created
based on the current parent's value (or RUNTIME_INF in the case of
root_task_group). Otherwise, the field is wrong until a quota is
changed after creation and __cfs_schedulable() is called.
Fixes: c53593e5cb ("sched, cgroup: Don't reject lower cpu.max on ancestors")
Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230714125746.812891-1-pauld@redhat.com
Revert commit 7aa55f2a59 ("sched/fair: Move unused stub functions to
header"), for while it has the right Changelog, the actual patch
content a revert of the previous 4 patches:
f7df852ad6 ("sched: Make task_vruntime_update() prototype visible")
c0bdfd72fb ("sched/fair: Hide unused init_cfs_bandwidth() stub")
378be384e0 ("sched: Add schedule_user() declaration")
d55ebae3f3 ("sched: Hide unused sched_update_scaling()")
So in effect this is a revert of a revert and re-applies those
patches.
Fixes: 7aa55f2a59 ("sched/fair: Move unused stub functions to header")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
The flags of the child of a given scheduling domain are used to initialize
the flags of its scheduling groups. When the child of a scheduling domain
is degenerated, the flags of its local scheduling group need to be updated
to align with the flags of its new child domain.
The flag SD_SHARE_CPUCAPACITY was aligned in
Commit bf2dc42d6b ("sched/topology: Propagate SMT flags when removing degenerate domain").
Further generalize this alignment so other flags can be used later, such as
in cluster-based task wakeup. [1]
Reported-by: Yicong Yang <yangyicong@huawei.com>
Suggested-by: Ricardo Neri <ricardo.neri@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Yicong Yang <yangyicong@hisilicon.com>
Link: https://lore.kernel.org/r/20230713013133.2314153-1-yu.c.chen@intel.com
There is no need to use runnable_avg when estimating util_est and that
even generates wrong behavior because one includes blocked tasks whereas
the other one doesn't. This can lead to accounting twice the waking task p,
once with the blocked runnable_avg and another one when adding its
util_est.
cpu's runnable_avg is already used when computing util_avg which is then
compared with util_est.
In some situation, feec will not select prev_cpu but another one on the
same performance domain because of higher max_util
Fixes: 7d0583cf9e ("sched/fair, cpufreq: Introduce 'runnable boosting'")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20230706135144.324311-1-vincent.guittot@linaro.org
EEVDF uses this tunable as the base request/slice -- make sure the
name reflects this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124604.205287511@infradead.org
EEVDF is a better defined scheduling policy, as a result it has less
heuristics/tunables. There is no compelling reason to keep CFS around.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124604.137187212@infradead.org
Using lag is both more correct and simpler when moving between
runqueues.
Notable, min_vruntime() was invented as a cheap approximation of
avg_vruntime() for this very purpose (SMP migration). Since we now
have the real thing; use it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124604.068911180@infradead.org
Removes the FAIR_SLEEPERS code in favour of the new LAG based
placement.
Specifically, the whole FAIR_SLEEPER thing was a very crude
approximation to make up for the lack of lag based placement,
specifically the 'service owed' part. This is important for things
like 'starve' and 'hackbench'.
One side effect of FAIR_SLEEPER is that it caused 'small' unfairness,
specifically, by always ignoring up-to 'thresh' sleeptime it would
have a 50%/50% time distribution for a 50% sleeper vs a 100% runner,
while strictly speaking this should (of course) result in a 33%/67%
split (as CFS will also do if the sleep period exceeds 'thresh').
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124604.000198861@infradead.org
Where CFS is currently a WFQ based scheduler with only a single knob,
the weight. The addition of a second, latency oriented parameter,
makes something like WF2Q or EEVDF based a much better fit.
Specifically, EEVDF does EDF like scheduling in the left half of the
tree -- those entities that are owed service. Except because this is a
virtual time scheduler, the deadlines are in virtual time as well,
which is what allows over-subscription.
EEVDF has two parameters:
- weight, or time-slope: which is mapped to nice just as before
- request size, or slice length: which is used to compute
the virtual deadline as: vd_i = ve_i + r_i/w_i
Basically, by setting a smaller slice, the deadline will be earlier
and the task will be more eligible and ran earlier.
Tick driven preemption is driven by request/slice completion; while
wakeup preemption is driven by the deadline.
Because the tree is now effectively an interval tree, and the
selection is no longer 'leftmost', over-scheduling is less of a
problem.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124603.931005524@infradead.org
With the introduction of avg_vruntime, it is possible to approximate
lag (the entire purpose of introducing it in fact). Use this to do lag
based placement over sleep+wake.
Specifically, the FAIR_SLEEPERS thing places things too far to the
left and messes up the deadline aspect of EEVDF.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124603.794929315@infradead.org
With the introduction of avg_vruntime() there is no need to use worse
approximations. Take the 0-lag point as starting point for inserting
new tasks.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124603.722361178@infradead.org
In order to move to an eligibility based scheduling policy, we need
to have a better approximation of the ideal scheduler.
Specifically, for a virtual time weighted fair queueing based
scheduler the ideal scheduler will be the weighted average of the
individual virtual runtimes (math in the comment).
As such, compute the weighted average to approximate the ideal
scheduler -- note that the approximation is in the individual task
behaviour, which isn't strictly conformant.
Specifically consider adding a task with a vruntime left of center, in
this case the average will move backwards in time -- something the
ideal scheduler would of course never do.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230531124603.654144274@infradead.org
Add complete_on_current_cpu, wake_up_poll_on_current_cpu helpers to wake
up tasks on the current CPU.
These two helpers are useful when the task needs to make a synchronous context
switch to another task. In this context, synchronous means it wakes up the
target task and falls asleep right after that.
One example of such workloads is seccomp user notifies. This mechanism allows
the supervisor process handles system calls on behalf of a target process.
While the supervisor is handling an intercepted system call, the target process
will be blocked in the kernel, waiting for a response to come back.
On-CPU context switches are much faster than regular ones.
Signed-off-by: Andrei Vagin <avagin@google.com>
Acked-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230308073201.3102738-4-avagin@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Add WF_CURRENT_CPU wake flag that advices the scheduler to
move the wakee to the current CPU. This is useful for fast on-CPU
context switching use cases.
In addition, make ttwu external rather than static so that
the flag could be passed to it from outside of sched/core.c.
Signed-off-by: Peter Oskolkov <posk@google.com>
Signed-off-by: Andrei Vagin <avagin@google.com>
Acked-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230308073201.3102738-3-avagin@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
select_idle_capacity() not only looks for an idle cpu that fits for the
waking task but also for cpu with highest bandwidth when no cpu fits.
Start the loop with target cpu so it will be selected 1st when no cpu fits
but several cpus shared the same bandwidth. Starting with target cpu
prevents the task to migrate between cpus with same bandwidth at every
wakeup when no cpu fits.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230711081359.868862-1-vincent.guittot@linaro.org
There have been a case where the SD_SHARE_CPUCAPACITY sched group flag
in a parent domain were not set and propagated properly when a degenerate
domain is removed.
Add dump of domain sched group flags of a CPU to make debug easier
in the future.
Usage:
cat /debug/sched/domains/cpu0/domain1/groups_flags
to dump cpu0 domain1's sched group flags.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/ed1749262d94d95a8296c86a415999eda90bcfe3.1688770494.git.tim.c.chen@linux.intel.com
should_we_balance() traverses the group_balance_mask (AND'ed with lb_env::
cpus) starting from lower numbered CPUs looking for the first idle CPU.
In hybrid x86 systems, the siblings of SMT cores get CPU numbers, before
non-SMT cores:
[0, 1] [2, 3] [4, 5] 6 7 8 9
b i b i b i b i i i
In the figure above, CPUs in brackets are siblings of an SMT core. The
rest are non-SMT cores. 'b' indicates a busy CPU, 'i' indicates an
idle CPU.
We should let a CPU on a fully idle core get the first chance to idle
load balance as it has more CPU capacity than a CPU on an idle SMT
CPU with busy sibling. So for the figure above, if we are running
should_we_balance() to CPU 1, we should return false to let CPU 7 on
idle core to have a chance first to idle load balance.
A partially busy (i.e., of type group_has_spare) local group with SMT
cores will often have only one SMT sibling busy. If the destination CPU
is a non-SMT core, partially busy, lower-numbered, SMT cores should not
be considered when finding the first idle CPU.
However, in should_we_balance(), when we encounter idle SMT first in partially
busy core, we prematurely break the search for the first idle CPU.
Higher-numbered, non-SMT cores is not given the chance to have
idle balance done on their behalf. Those CPUs will only be considered
for idle balancing by chance via CPU_NEWLY_IDLE.
Instead, consider the idle state of the whole SMT core.
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Co-developed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/807bdd05331378ea3bf5956bda87ded1036ba769.1688770494.git.tim.c.chen@linux.intel.com
In the current prefer sibling load balancing code, there is an implicit
assumption that the busiest sched group and local sched group are
equivalent, hence the tasks to be moved is simply the difference in
number of tasks between the two groups (i.e. imbalance) divided by two.
However, we may have different number of cores between the cluster groups,
say when we take CPU offline or we have hybrid groups. In that case,
we should balance between the two groups such that #tasks/#cores ratio
is the same between the same between both groups. Hence the imbalance
computed will need to reflect this.
Adjust the sibling imbalance computation to take into account of the
above considerations.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/4eacbaa236e680687dae2958378a6173654113df.1688770494.git.tim.c.chen@linux.intel.com
When balancing sibling domains that have different number of cores,
tasks in respective sibling domain should be proportional to the
number of cores in each domain. In preparation of implementing such a
policy, record the number of cores in a scheduling group.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/04641eeb0e95c21224352f5743ecb93dfac44654.1688770494.git.tim.c.chen@linux.intel.com
On hybrid CPUs with scheduling cluster enabled, we will need to
consider balancing between SMT CPU cluster, and Atom core cluster.
Below shows such a hybrid x86 CPU with 4 big cores and 8 atom cores.
Each scheduling cluster span a L2 cache.
--L2-- --L2-- --L2-- --L2-- ----L2---- -----L2------
[0, 1] [2, 3] [4, 5] [5, 6] [7 8 9 10] [11 12 13 14]
Big Big Big Big Atom Atom
core core core core Module Module
If the busiest group is a big core with both SMT CPUs busy, we should
active load balance if destination group has idle CPU cores. Such
condition is considered by asym_active_balance() in load balancing but not
considered when looking for busiest group and computing load imbalance.
Add this consideration in find_busiest_group() and calculate_imbalance().
In addition, update the logic determining the busier group when one group
is SMT and the other group is non SMT but both groups are partially busy
with idle CPU. The busier group should be the group with idle cores rather
than the group with one busy SMT CPU. We do not want to make the SMT group
the busiest one to pull the only task off SMT CPU and causing the whole core to
go empty.
Otherwise suppose in the search for the busiest group, we first encounter
an SMT group with 1 task and set it as the busiest. The destination
group is an atom cluster with 1 task and we next encounter an atom
cluster group with 3 tasks, we will not pick this atom cluster over the
SMT group, even though we should. As a result, we do not load balance
the busier Atom cluster (with 3 tasks) towards the local atom cluster
(with 1 task). And it doesn't make sense to pick the 1 task SMT group
as the busier group as we also should not pull task off the SMT towards
the 1 task atom cluster and make the SMT core completely empty.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/e24f35d142308790f69be65930b82794ef6658a2.1688770494.git.tim.c.chen@linux.intel.com
The static key psi_cgroups_enabled is only used inside file psi.c.
Make it static.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Link: https://lore.kernel.org/r/20230525103428.49712-1-linmiaohe@huawei.com
As core scheduling introduced, a new state of idle is defined as
force idle, running idle task but nr_running greater than zero.
If a cpu is in force idle state, idle_cpu() will return zero. This
result makes sense in some scenarios, e.g., load balance,
showacpu when dumping, and judge the RCU boost kthread is starving.
But this will cause error in other scenarios, e.g., tick_irq_exit():
When force idle, rq->curr == rq->idle but rq->nr_running > 0, results
that idle_cpu() returns 0. In function tick_irq_exit(), if idle_cpu()
is 0, tick_nohz_irq_exit() will not be called, and ts->idle_active will
not become 1, which became 0 in tick_nohz_irq_enter().
ts->idle_sleeptime won't update in function update_ts_time_stats(), if
ts->idle_active is 0, which should be 1. And this bug will result that
ts->idle_sleeptime is less than the actual value, and finally will
result that the idle time in /proc/stat is less than the actual value.
To solve this problem, we introduce sched_core_idle_cpu(), which
returns 1 when force idle. We audit all users of idle_cpu(), and
change idle_cpu() into sched_core_idle_cpu() in function
tick_irq_exit().
v2-->v3: Only replace idle_cpu() with sched_core_idle_cpu() in
function tick_irq_exit(). And modify the corresponding commit log.
Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Joel Fernandes <joel@joelfernandes.org>
Link: https://lore.kernel.org/r/1688011324-42406-1-git-send-email-CruzZhao@linux.alibaba.com
We currently export the total throttled time for cgroups that are given
a bandwidth limit. This patch extends this accounting to also account
the total time that each children cgroup has been throttled.
This is useful to understand the degree to which children have been
affected by the throttling control. Children which are not runnable
during the entire throttled period, for example, will not show any
self-throttling time during this period.
Expose this in a new interface, 'cpu.stat.local', which is similar to
how non-hierarchical events are accounted in 'memory.events.local'.
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230620183247.737942-2-joshdon@google.com
It is easy for a cfs_rq to become throttled even when it has no enqueued
entities (for example, if we have just put_prev()'d the last runnable
task of the cfs_rq, and the cfs_rq is out of quota).
Avoid accounting this time towards total throttle time, since it
otherwise falsely inflates the stats.
Note that the dequeue path is special, since we normally disallow
migrations when a task is in a throttled hierarchy (see
throttled_lb_pair()).
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230620183247.737942-1-joshdon@google.com
Destroying psi trigger in cgroup_file_release causes UAF issues when
a cgroup is removed from under a polling process. This is happening
because cgroup removal causes a call to cgroup_file_release while the
actual file is still alive. Destroying the trigger at this point would
also destroy its waitqueue head and if there is still a polling process
on that file accessing the waitqueue, it will step on the freed pointer:
do_select
vfs_poll
do_rmdir
cgroup_rmdir
kernfs_drain_open_files
cgroup_file_release
cgroup_pressure_release
psi_trigger_destroy
wake_up_pollfree(&t->event_wait)
// vfs_poll is unblocked
synchronize_rcu
kfree(t)
poll_freewait -> UAF access to the trigger's waitqueue head
Patch [1] fixed this issue for epoll() case using wake_up_pollfree(),
however the same issue exists for synchronous poll() case.
The root cause of this issue is that the lifecycles of the psi trigger's
waitqueue and of the file associated with the trigger are different. Fix
this by using kernfs_generic_poll function when polling on cgroup-specific
psi triggers. It internally uses kernfs_open_node->poll waitqueue head
with its lifecycle tied to the file's lifecycle. This also renders the
fix in [1] obsolete, so revert it.
[1] commit c2dbe32d5d ("sched/psi: Fix use-after-free in ep_remove_wait_queue()")
Fixes: 0e94682b73 ("psi: introduce psi monitor")
Closes: https://lore.kernel.org/all/20230613062306.101831-1-lujialin4@huawei.com/
Reported-by: Lu Jialin <lujialin4@huawei.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230630005612.1014540-1-surenb@google.com
When checking whether a recently used CPU can be a potential idle
candidate, recent_used_cpu should be used to test p->cpus_ptr as
p->recent_used_cpu is not equal to recent_used_cpu and candidate
decision is made based on recent_used_cpu here.
Fixes: 89aafd67f2 ("sched/fair: Use prev instead of new target as recent_used_cpu")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20230620080747.359122-1-linmiaohe@huawei.com
* Whenever cpuset needs to rebuild sched_domain, it walked all tasks looking
for DEADLINE tasks as they need to be accounted on the new domain. Walking
all tasks can be expensive and there may not be any DEADLINE tasks at all.
Task iteration is now omitted if there are no DEADLINE tasks.
* Fixes DEADLINE bandwidth misaccounting after task migration failures.
* When no controller is enabled, -Wstringop-overflow warning is triggered.
The fix patch added an early exit which is too eager and got reverted for
now. Will fix later.
* Everything else are minor cleanups.
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Merge tag 'cgroup-for-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
- Whenever cpuset needs to rebuild sched_domain, it walked all tasks
looking for DEADLINE tasks as they need to be accounted on the new
domain. Walking all tasks can be expensive and there may not be any
DEADLINE tasks at all. Task iteration is now omitted if there are no
DEADLINE tasks
- Fixes DEADLINE bandwidth misaccounting after task migration failures
- When no controller is enabled, -Wstringop-overflow warning is
triggered. The fix patch added an early exit which is too eager and
got reverted for now. Will fix later
- Everything else is minor cleanups
* tag 'cgroup-for-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
Revert "cgroup: Avoid -Wstringop-overflow warnings"
cgroup/misc: Expose misc.current on cgroup v2 root
cgroup: Avoid -Wstringop-overflow warnings
cgroup: remove obsolete comment on cgroup_on_dfl()
cgroup: remove unused task_cgroup_path()
cgroup/cpuset: remove unneeded header files
cgroup: make cgroup_is_threaded() and cgroup_is_thread_root() static
rdmacg: fix kernel-doc warnings in rdmacg
cgroup: Replace the css_set call with cgroup_get
cgroup: remove unused macro for_each_e_css()
cgroup: Update out-of-date comment in cgroup_migrate()
cgroup: Replace all non-returning strlcpy with strscpy
cgroup/cpuset: remove unneeded header files
cgroup/cpuset: Free DL BW in case can_attach() fails
sched/deadline: Create DL BW alloc, free & check overflow interface
cgroup/cpuset: Iterate only if DEADLINE tasks are present
sched/cpuset: Keep track of SCHED_DEADLINE task in cpusets
sched/cpuset: Bring back cpuset_mutex
cgroup/cpuset: Rename functions dealing with DEADLINE accounting
* Concurrency-managed per-cpu work items that hog CPUs and delay the
execution of other work items are now automatically detected and excluded
from concurrency management. Reporting on such work items can also be
enabled through a config option.
* Added tools/workqueue/wq_monitor.py which improves visibility into
workqueue usages and behaviors.
* Includes Arnd's minimal fix for gcc-13 enum warning on 32bit compiles.
This conflicts with afa4bb778e ("workqueue: clean up WORK_* constant
types, clarify masking") in master. Can be resolved by picking the master
version.
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Merge tag 'wq-for-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue updates from Tejun Heo:
- Concurrency-managed per-cpu work items that hog CPUs and delay the
execution of other work items are now automatically detected and
excluded from concurrency management. Reporting on such work items
can also be enabled through a config option.
- Added tools/workqueue/wq_monitor.py which improves visibility into
workqueue usages and behaviors.
- Arnd's minimal fix for gcc-13 enum warning on 32bit compiles,
superseded by commit afa4bb778e in mainline.
* tag 'wq-for-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Disable per-cpu CPU hog detection when wq_cpu_intensive_thresh_us is 0
workqueue: Fix WARN_ON_ONCE() triggers in worker_enter_idle()
workqueue: fix enum type for gcc-13
workqueue: Track and monitor per-workqueue CPU time usage
workqueue: Report work funcs that trigger automatic CPU_INTENSIVE mechanism
workqueue: Automatically mark CPU-hogging work items CPU_INTENSIVE
workqueue: Improve locking rule description for worker fields
workqueue: Move worker_set/clr_flags() upwards
workqueue: Re-order struct worker fields
workqueue: Add pwq->stats[] and a monitoring script
Further upgrade queue_work_on() comment
- Introduce cmpxchg128() -- aka. the demise of cmpxchg_double().
The cmpxchg128() family of functions is basically & functionally
the same as cmpxchg_double(), but with a saner interface: instead
of a 6-parameter horror that forced u128 - u64/u64-halves layout
details on the interface and exposed users to complexity,
fragility & bugs, use a natural 3-parameter interface with u128 types.
- Restructure the generated atomic headers, and add
kerneldoc comments for all of the generic atomic{,64,_long}_t
operations. Generated definitions are much cleaner now,
and come with documentation.
- Implement lock_set_cmp_fn() on lockdep, for defining an ordering
when taking multiple locks of the same type. This gets rid of
one use of lockdep_set_novalidate_class() in the bcache code.
- Fix raw_cpu_generic_try_cmpxchg() bug due to an unintended
variable shadowing generating garbage code on Clang on certain
ARM builds.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
- Introduce cmpxchg128() -- aka. the demise of cmpxchg_double()
The cmpxchg128() family of functions is basically & functionally the
same as cmpxchg_double(), but with a saner interface.
Instead of a 6-parameter horror that forced u128 - u64/u64-halves
layout details on the interface and exposed users to complexity,
fragility & bugs, use a natural 3-parameter interface with u128
types.
- Restructure the generated atomic headers, and add kerneldoc comments
for all of the generic atomic{,64,_long}_t operations.
The generated definitions are much cleaner now, and come with
documentation.
- Implement lock_set_cmp_fn() on lockdep, for defining an ordering when
taking multiple locks of the same type.
This gets rid of one use of lockdep_set_novalidate_class() in the
bcache code.
- Fix raw_cpu_generic_try_cmpxchg() bug due to an unintended variable
shadowing generating garbage code on Clang on certain ARM builds.
* tag 'locking-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
locking/atomic: scripts: fix ${atomic}_dec_if_positive() kerneldoc
percpu: Fix self-assignment of __old in raw_cpu_generic_try_cmpxchg()
locking/atomic: treewide: delete arch_atomic_*() kerneldoc
locking/atomic: docs: Add atomic operations to the driver basic API documentation
locking/atomic: scripts: generate kerneldoc comments
docs: scripts: kernel-doc: accept bitwise negation like ~@var
locking/atomic: scripts: simplify raw_atomic*() definitions
locking/atomic: scripts: simplify raw_atomic_long*() definitions
locking/atomic: scripts: split pfx/name/sfx/order
locking/atomic: scripts: restructure fallback ifdeffery
locking/atomic: scripts: build raw_atomic_long*() directly
locking/atomic: treewide: use raw_atomic*_<op>()
locking/atomic: scripts: add trivial raw_atomic*_<op>()
locking/atomic: scripts: factor out order template generation
locking/atomic: scripts: remove leftover "${mult}"
locking/atomic: scripts: remove bogus order parameter
locking/atomic: xtensa: add preprocessor symbols
locking/atomic: x86: add preprocessor symbols
locking/atomic: sparc: add preprocessor symbols
locking/atomic: sh: add preprocessor symbols
...
- Scheduler SMP load-balancer improvements:
- Avoid unnecessary migrations within SMT domains on hybrid systems.
Problem:
On hybrid CPU systems, (processors with a mixture of higher-frequency
SMT cores and lower-frequency non-SMT cores), under the old code
lower-priority CPUs pulled tasks from the higher-priority cores if
more than one SMT sibling was busy - resulting in many unnecessary
task migrations.
Solution:
The new code improves the load balancer to recognize SMT cores with more
than one busy sibling and allows lower-priority CPUs to pull tasks, which
avoids superfluous migrations and lets lower-priority cores inspect all SMT
siblings for the busiest queue.
- Implement the 'runnable boosting' feature in the EAS balancer: consider CPU
contention in frequency, EAS max util & load-balance busiest CPU selection.
This improves CPU utilization for certain workloads, while leaves other key
workloads unchanged.
- Scheduler infrastructure improvements:
- Rewrite the scheduler topology setup code by consolidating it
into the build_sched_topology() helper function and building
it dynamically on the fly.
- Resolve the local_clock() vs. noinstr complications by rewriting
the code: provide separate sched_clock_noinstr() and
local_clock_noinstr() functions to be used in instrumentation code,
and make sure it is all instrumentation-safe.
- Fixes:
- Fix a kthread_park() race with wait_woken()
- Fix misc wait_task_inactive() bugs unearthed by the -rt merge:
- Fix UP PREEMPT bug by unifying the SMP and UP implementations.
- Fix task_struct::saved_state handling.
- Fix various rq clock update bugs, unearthed by turning on the rq clock
debugging code.
- Fix the PSI WINDOW_MIN_US trigger limit, which was easy to trigger by
creating enough cgroups, by removing the warnign and restricting
window size triggers to PSI file write-permission or CAP_SYS_RESOURCE.
- Propagate SMT flags in the topology when removing degenerate domain
- Fix grub_reclaim() calculation bug in the deadline scheduler code
- Avoid resetting the min update period when it is unnecessary, in
psi_trigger_destroy().
- Don't balance a task to its current running CPU in load_balance(),
which was possible on certain NUMA topologies with overlapping
groups.
- Fix the sched-debug printing of rq->nr_uninterruptible
- Cleanups:
- Address various -Wmissing-prototype warnings, as a preparation
to (maybe) enable this warning in the future.
- Remove unused code
- Mark more functions __init
- Fix shadow-variable warnings
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Scheduler SMP load-balancer improvements:
- Avoid unnecessary migrations within SMT domains on hybrid systems.
Problem:
On hybrid CPU systems, (processors with a mixture of
higher-frequency SMT cores and lower-frequency non-SMT cores),
under the old code lower-priority CPUs pulled tasks from the
higher-priority cores if more than one SMT sibling was busy -
resulting in many unnecessary task migrations.
Solution:
The new code improves the load balancer to recognize SMT cores
with more than one busy sibling and allows lower-priority CPUs
to pull tasks, which avoids superfluous migrations and lets
lower-priority cores inspect all SMT siblings for the busiest
queue.
- Implement the 'runnable boosting' feature in the EAS balancer:
consider CPU contention in frequency, EAS max util & load-balance
busiest CPU selection.
This improves CPU utilization for certain workloads, while leaves
other key workloads unchanged.
Scheduler infrastructure improvements:
- Rewrite the scheduler topology setup code by consolidating it into
the build_sched_topology() helper function and building it
dynamically on the fly.
- Resolve the local_clock() vs. noinstr complications by rewriting
the code: provide separate sched_clock_noinstr() and
local_clock_noinstr() functions to be used in instrumentation code,
and make sure it is all instrumentation-safe.
Fixes:
- Fix a kthread_park() race with wait_woken()
- Fix misc wait_task_inactive() bugs unearthed by the -rt merge:
- Fix UP PREEMPT bug by unifying the SMP and UP implementations
- Fix task_struct::saved_state handling
- Fix various rq clock update bugs, unearthed by turning on the rq
clock debugging code.
- Fix the PSI WINDOW_MIN_US trigger limit, which was easy to trigger
by creating enough cgroups, by removing the warnign and restricting
window size triggers to PSI file write-permission or
CAP_SYS_RESOURCE.
- Propagate SMT flags in the topology when removing degenerate domain
- Fix grub_reclaim() calculation bug in the deadline scheduler code
- Avoid resetting the min update period when it is unnecessary, in
psi_trigger_destroy().
- Don't balance a task to its current running CPU in load_balance(),
which was possible on certain NUMA topologies with overlapping
groups.
- Fix the sched-debug printing of rq->nr_uninterruptible
Cleanups:
- Address various -Wmissing-prototype warnings, as a preparation to
(maybe) enable this warning in the future.
- Remove unused code
- Mark more functions __init
- Fix shadow-variable warnings"
* tag 'sched-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle()
sched/core: Avoid double calling update_rq_clock() in __balance_push_cpu_stop()
sched/core: Fixed missing rq clock update before calling set_rq_offline()
sched/deadline: Update GRUB description in the documentation
sched/deadline: Fix bandwidth reclaim equation in GRUB
sched/wait: Fix a kthread_park race with wait_woken()
sched/topology: Mark set_sched_topology() __init
sched/fair: Rename variable cpu_util eff_util
arm64/arch_timer: Fix MMIO byteswap
sched/fair, cpufreq: Introduce 'runnable boosting'
sched/fair: Refactor CPU utilization functions
cpuidle: Use local_clock_noinstr()
sched/clock: Provide local_clock_noinstr()
x86/tsc: Provide sched_clock_noinstr()
clocksource: hyper-v: Provide noinstr sched_clock()
clocksource: hyper-v: Adjust hv_read_tsc_page_tsc() to avoid special casing U64_MAX
x86/vdso: Fix gettimeofday masking
math64: Always inline u128 version of mul_u64_u64_shr()
s390/time: Provide sched_clock_noinstr()
loongarch: Provide noinstr sched_clock_read()
...
After commit 8ad075c2eb ("sched: Async unthrottling for cfs
bandwidth"), we may update the rq clock multiple times in the loop of
__cfsb_csd_unthrottle().
A prior (although less common) instance of this problem exists in
unthrottle_offline_cfs_rqs().
Cure both by ensuring update_rq_clock() is called before the loop and
setting RQCF_ACT_SKIP during the loop, to supress further updates.
The alternative would be pulling update_rq_clock() out of
unthrottle_cfs_rq(), but that gives an even bigger mess.
Fixes: 8ad075c2eb ("sched: Async unthrottling for cfs bandwidth")
Reviewed-By: Ben Segall <bsegall@google.com>
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20230613082012.49615-4-jiahao.os@bytedance.com
There is a double update_rq_clock() invocation:
__balance_push_cpu_stop()
update_rq_clock()
__migrate_task()
update_rq_clock()
Sadly select_fallback_rq() also needs update_rq_clock() for
__do_set_cpus_allowed(), it is not possible to remove the update from
__balance_push_cpu_stop(). So remove it from __migrate_task() and
ensure all callers of this function call update_rq_clock() prior to
calling it.
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20230613082012.49615-3-jiahao.os@bytedance.com
When using a cpufreq governor that uses
cpufreq_add_update_util_hook(), it is possible to trigger a missing
update_rq_clock() warning for the CPU hotplug path:
rq_attach_root()
set_rq_offline()
rq_offline_rt()
__disable_runtime()
sched_rt_rq_enqueue()
enqueue_top_rt_rq()
cpufreq_update_util()
data->func(data, rq_clock(rq), flags)
Move update_rq_clock() from sched_cpu_deactivate() (one of it's
callers) into set_rq_offline() such that it covers all
set_rq_offline() usage.
Additionally change rq_attach_root() to use rq_lock_irqsave() so that
it will properly manage the runqueue clock flags.
Suggested-by: Ben Segall <bsegall@google.com>
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20230613082012.49615-2-jiahao.os@bytedance.com
According to the GRUB[1] rule, the runtime is depreciated as:
"dq = -max{u, (1 - Uinact - Uextra)} dt" (1)
To guarantee that deadline tasks doesn't starve lower class tasks,
we do not allocate the full bandwidth of the cpu to deadline tasks.
Maximum bandwidth usable by deadline tasks is denoted by "Umax".
Considering Umax, equation (1) becomes:
"dq = -(max{u, (Umax - Uinact - Uextra)} / Umax) dt" (2)
Current implementation has a minor bug in equation (2), which this
patch fixes.
The reclamation logic is verified by a sample program which creates
multiple deadline threads and observing their utilization. The tests
were run on an isolated cpu(isolcpus=3) on a 4 cpu system.
Tests on 6.3.0
==============
RUN 1: runtime=7ms, deadline=period=10ms, RT capacity = 95%
TID[693]: RECLAIM=1, (r=7ms, d=10ms, p=10ms), Util: 93.33
TID[693]: RECLAIM=1, (r=7ms, d=10ms, p=10ms), Util: 93.35
RUN 2: runtime=1ms, deadline=period=100ms, RT capacity = 95%
TID[708]: RECLAIM=1, (r=1ms, d=100ms, p=100ms), Util: 16.69
TID[708]: RECLAIM=1, (r=1ms, d=100ms, p=100ms), Util: 16.69
RUN 3: 2 tasks
Task 1: runtime=1ms, deadline=period=10ms
Task 2: runtime=1ms, deadline=period=100ms
TID[631]: RECLAIM=1, (r=1ms, d=10ms, p=10ms), Util: 62.67
TID[632]: RECLAIM=1, (r=1ms, d=100ms, p=100ms), Util: 6.37
TID[631]: RECLAIM=1, (r=1ms, d=10ms, p=10ms), Util: 62.38
TID[632]: RECLAIM=1, (r=1ms, d=100ms, p=100ms), Util: 6.23
As seen above, the reclamation doesn't reclaim the maximum allowed
bandwidth and as the bandwidth of tasks gets smaller, the reclaimed
bandwidth also comes down.
Tests with this patch applied
=============================
RUN 1: runtime=7ms, deadline=period=10ms, RT capacity = 95%
TID[608]: RECLAIM=1, (r=7ms, d=10ms, p=10ms), Util: 95.19
TID[608]: RECLAIM=1, (r=7ms, d=10ms, p=10ms), Util: 95.16
RUN 2: runtime=1ms, deadline=period=100ms, RT capacity = 95%
TID[616]: RECLAIM=1, (r=1ms, d=100ms, p=100ms), Util: 95.27
TID[616]: RECLAIM=1, (r=1ms, d=100ms, p=100ms), Util: 95.21
RUN 3: 2 tasks
Task 1: runtime=1ms, deadline=period=10ms
Task 2: runtime=1ms, deadline=period=100ms
TID[620]: RECLAIM=1, (r=1ms, d=10ms, p=10ms), Util: 86.64
TID[621]: RECLAIM=1, (r=1ms, d=100ms, p=100ms), Util: 8.66
TID[620]: RECLAIM=1, (r=1ms, d=10ms, p=10ms), Util: 86.45
TID[621]: RECLAIM=1, (r=1ms, d=100ms, p=100ms), Util: 8.73
Running tasks on all cpus allowing for migration also showed that
the utilization is reclaimed to the maximum. Running 10 tasks on
3 cpus SCHED_FLAG_RECLAIM - top shows:
%Cpu0 : 94.6 us, 0.0 sy, 0.0 ni, 5.4 id, 0.0 wa
%Cpu1 : 95.2 us, 0.0 sy, 0.0 ni, 4.8 id, 0.0 wa
%Cpu2 : 95.8 us, 0.0 sy, 0.0 ni, 4.2 id, 0.0 wa
[1]: Abeni, Luca & Lipari, Giuseppe & Parri, Andrea & Sun, Youcheng.
(2015). Parallel and sequential reclaiming in multicore
real-time global scheduling.
Signed-off-by: Vineeth Pillai (Google) <vineeth@bitbyteword.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20230530135526.2385378-1-vineeth@bitbyteword.org
kthread_park and wait_woken have a similar race that
kthread_stop and wait_woken used to have before it was fixed in
commit cb6538e740 ("sched/wait: Fix a kthread race with
wait_woken()"). Extend that fix to also cover kthread_park.
[jstultz: Made changes suggested by Peter to optimize
memory loads]
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20230602212350.535358-1-jstultz@google.com
All callers of set_sched_topology() are within __init section. Mark
it __init too.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20230603073645.1173332-1-linmiaohe@huawei.com
cppcheck reports
kernel/sched/fair.c:7436:17: style: Local variable 'cpu_util' shadows outer function [shadowFunction]
unsigned long cpu_util;
^
Clean this up by renaming the variable to eff_util
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20230611122535.183654-1-trix@redhat.com
The responsiveness of the Per Entity Load Tracking (PELT) util_avg in
mobile devices is still considered too low for utilization changes
during task ramp-up.
In Android this manifests in the fact that the first frames of a UI
activity are very prone to be jankframes (a frame which doesn't meet
the required frame rendering time, e.g. 16ms@60Hz) since the CPU
frequency is normally low at this point and has to ramp up quickly.
The beginning of an UI activity is also characterized by the occurrence
of CPU contention, especially on little CPUs. Current little CPUs can
have an original CPU capacity of only ~ 150 which means that the actual
CPU capacity at lower frequency can even be much smaller.
Schedutil maps CPU util_avg into CPU frequency request via:
util = effective_cpu_util(..., cpu_util_cfs(cpu), ...) ->
util = map_util_perf(util) -> freq = map_util_freq(util, ...)
CPU contention for CFS tasks can be detected by 'CPU runnable > CPU
utililization' in cpu_util_cfs_boost() -> cpu_util(..., boost = 1).
Schedutil uses 'runnable boosting' by calling cpu_util_cfs_boost().
To be in sync with schedutil's CPU frequency selection, Energy Aware
Scheduling (EAS) also calls cpu_util(..., boost = 1) during max util
detection.
Moreover, 'runnable boosting' is also used in load-balance for busiest
CPU selection when the migration type is 'migrate_util', i.e. only at
sched domains which don't have the SD_SHARE_PKG_RESOURCES flag set.
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230515115735.296329-3-dietmar.eggemann@arm.com
There is a lot of code duplication in cpu_util_next() & cpu_util_cfs().
Remove this by allowing cpu_util_next() to be called with p = NULL.
Rename cpu_util_next() to cpu_util() since the '_next' suffix is no
longer necessary to distinct cpu utilization related functions.
Implement cpu_util_cfs(cpu) as cpu_util(cpu, p = NULL, -1).
This will allow to code future related cpu util changes only in one
place, namely in cpu_util().
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230515115735.296329-2-dietmar.eggemann@arm.com
Now that all ARCH_WANTS_NO_INSTR architectures (arm64, loongarch,
s390, x86) provide sched_clock_noinstr(), use this to provide
local_clock_noinstr().
This local_clock_noinstr() will be safe to use from noinstr code with
the assumption that any such noinstr code is non-preemptible (it had
better be, entry code will have IRQs disabled while __cpuidle must
have preemption disabled).
Specifically, preempt_enable_notrace(), a common part of many a
sched_clock() implementation calls out to schedule() -- even though,
per the above, it will never trigger -- which frustrates noinstr
validation.
vmlinux.o: warning: objtool: local_clock+0xb5: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com> # Hyper-V
Link: https://lore.kernel.org/r/20230519102715.978624636@infradead.org
With the introduction of task_struct::saved_state in commit
5f220be214 ("sched/wakeup: Prepare for RT sleeping spin/rwlocks")
matching the task state has gotten more complicated. That same commit
changed try_to_wake_up() to consider both states, but
wait_task_inactive() has been neglected.
Sebastian noted that the wait_task_inactive() usage in
ptrace_check_attach() can misbehave when ptrace_stop() is blocked on
the tasklist_lock after it sets TASK_TRACED.
Therefore extract a common helper from ttwu_state_match() and use that
to teach wait_task_inactive() about the PREEMPT_RT locks.
Originally-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lkml.kernel.org/r/20230601091234.GW83892@hirez.programming.kicks-ass.net
While modifying wait_task_inactive() for PREEMPT_RT; the build robot
noted that UP got broken. This led to audit and consideration of the
UP implementation of wait_task_inactive().
It looks like the UP implementation is also broken for PREEMPT;
consider task_current_syscall() getting preempted between the two
calls to wait_task_inactive().
Therefore move the wait_task_inactive() implementation out of
CONFIG_SMP and unconditionally use it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230602103731.GA630648%40hirez.programming.kicks-ass.net
We've run into the case that the balancer tries to balance a migration
disabled task and trigger the warning in set_task_cpu() like below:
------------[ cut here ]------------
WARNING: CPU: 7 PID: 0 at kernel/sched/core.c:3115 set_task_cpu+0x188/0x240
Modules linked in: hclgevf xt_CHECKSUM ipt_REJECT nf_reject_ipv4 <...snip>
CPU: 7 PID: 0 Comm: swapper/7 Kdump: loaded Tainted: G O 6.1.0-rc4+ #1
Hardware name: Huawei TaiShan 2280 V2/BC82AMDC, BIOS 2280-V2 CS V5.B221.01 12/09/2021
pstate: 604000c9 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : set_task_cpu+0x188/0x240
lr : load_balance+0x5d0/0xc60
sp : ffff80000803bc70
x29: ffff80000803bc70 x28: ffff004089e190e8 x27: ffff004089e19040
x26: ffff007effcabc38 x25: 0000000000000000 x24: 0000000000000001
x23: ffff80000803be84 x22: 000000000000000c x21: ffffb093e79e2a78
x20: 000000000000000c x19: ffff004089e19040 x18: 0000000000000000
x17: 0000000000001fad x16: 0000000000000030 x15: 0000000000000000
x14: 0000000000000003 x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000001 x10: 0000000000000400 x9 : ffffb093e4cee530
x8 : 00000000fffffffe x7 : 0000000000ce168a x6 : 000000000000013e
x5 : 00000000ffffffe1 x4 : 0000000000000001 x3 : 0000000000000b2a
x2 : 0000000000000b2a x1 : ffffb093e6d6c510 x0 : 0000000000000001
Call trace:
set_task_cpu+0x188/0x240
load_balance+0x5d0/0xc60
rebalance_domains+0x26c/0x380
_nohz_idle_balance.isra.0+0x1e0/0x370
run_rebalance_domains+0x6c/0x80
__do_softirq+0x128/0x3d8
____do_softirq+0x18/0x24
call_on_irq_stack+0x2c/0x38
do_softirq_own_stack+0x24/0x3c
__irq_exit_rcu+0xcc/0xf4
irq_exit_rcu+0x18/0x24
el1_interrupt+0x4c/0xe4
el1h_64_irq_handler+0x18/0x2c
el1h_64_irq+0x74/0x78
arch_cpu_idle+0x18/0x4c
default_idle_call+0x58/0x194
do_idle+0x244/0x2b0
cpu_startup_entry+0x30/0x3c
secondary_start_kernel+0x14c/0x190
__secondary_switched+0xb0/0xb4
---[ end trace 0000000000000000 ]---
Further investigation shows that the warning is superfluous, the migration
disabled task is just going to be migrated to its current running CPU.
This is because that on load balance if the dst_cpu is not allowed by the
task, we'll re-select a new_dst_cpu as a candidate. If no task can be
balanced to dst_cpu we'll try to balance the task to the new_dst_cpu
instead. In this case when the migration disabled task is not on CPU it
only allows to run on its current CPU, load balance will select its
current CPU as new_dst_cpu and later triggers the warning above.
The new_dst_cpu is chosen from the env->dst_grpmask. Currently it
contains CPUs in sched_group_span() and if we have overlapped groups it's
possible to run into this case. This patch makes env->dst_grpmask of
group_balance_mask() which exclude any CPUs from the busiest group and
solve the issue. For balancing in a domain with no overlapped groups
the behaviour keeps same as before.
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230530082507.10444-1-yangyicong@huawei.com
Now that we have raw_atomic*_<op>() definitions, there's no need to use
arch_atomic*_<op>() definitions outside of the low-level atomic
definitions.
Move treewide users of arch_atomic*_<op>() over to the equivalent
raw_atomic*_<op>().
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-19-mark.rutland@arm.com
The default deadline bandwidth control structure has been removed since
commit eb77cf1c15 ("sched/deadline: Remove unused def_dl_bandwidth")
leading to unused init_dl_bandwidth() and struct dl_bandwidth. Remove
them to clean up the code.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20230524102514.407486-1-linmiaohe@huawei.com
These four functions have a normal definition for CONFIG_FAIR_GROUP_SCHED,
and empty one that is only referenced when FAIR_GROUP_SCHED is disabled
but CGROUP_SCHED is still enabled. If both are turned off, the functions
are still defined but the misisng prototype causes a W=1 warning:
kernel/sched/fair.c:12544:6: error: no previous prototype for 'free_fair_sched_group'
kernel/sched/fair.c:12546:5: error: no previous prototype for 'alloc_fair_sched_group'
kernel/sched/fair.c:12553:6: error: no previous prototype for 'online_fair_sched_group'
kernel/sched/fair.c:12555:6: error: no previous prototype for 'unregister_fair_sched_group'
Move the alternatives into the header as static inline functions with
the correct combination of #ifdef checks to avoid the warning without
adding even more complexity.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-6-arnd@kernel.org
Having the prototype next to the caller but not visible to the callee causes
a W=1 warning:
kernel/sched/fair.c:11985:6: error: no previous prototype for 'task_vruntime_update' [-Werror=missing-prototypes]
Move this to a header, as we do for all other function declarations.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-5-arnd@kernel.org
init_cfs_bandwidth() is only used when CONFIG_FAIR_GROUP_SCHED is
enabled, and without this causes a W=1 warning for the missing prototype:
kernel/sched/fair.c:6131:6: error: no previous prototype for 'init_cfs_bandwidth'
The normal implementation is only defined for CONFIG_CFS_BANDWIDTH,
so the stub exists when CFS_BANDWIDTH is disabled but FAIR_GROUP_SCHED
is enabled.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-4-arnd@kernel.org
The schedule_user() function is used on powerpc and sparc architectures, but
only ever called from assembler, so it has no prototype, causing a harmless W=1
warning:
kernel/sched/core.c:6730:35: error: no previous prototype for 'schedule_user' [-Werror=missing-prototypes]
Add a prototype in sched/sched.h to shut up the warning.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-3-arnd@kernel.org
This function is only used when CONFIG_SMP is enabled, without that there
is no caller and no prototype:
kernel/sched/fair.c:688:5: error: no previous prototype for 'sched_update_scaling' [-Werror=missing-prototypes
Hide the definition in the same #ifdef check as the declaration.
Fixes: 8a99b6833c ("sched: Move SCHED_DEBUG sysctl to debugfs")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230522195021.3456768-2-arnd@kernel.org
Psi_group's poll_min_period is determined by the minimum window size of
psi_trigger when creating new triggers. While destroying a psi_trigger,
there is no need to reset poll_min_period if the psi_trigger being
destroyed did not have the minimum window size, since in this condition
poll_min_period will remain the same as before.
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Link: https://lkml.kernel.org/r/20230514163338.834345-1-surenb@google.com
If a per-cpu work item hogs the CPU, it can prevent other work items from
starting through concurrency management. A per-cpu workqueue which intends
to host such CPU-hogging work items can choose to not participate in
concurrency management by setting %WQ_CPU_INTENSIVE; however, this can be
error-prone and difficult to debug when missed.
This patch adds an automatic CPU usage based detection. If a
concurrency-managed work item consumes more CPU time than the threshold
(10ms by default) continuously without intervening sleeps, wq_worker_tick()
which is called from scheduler_tick() will detect the condition and
automatically mark it CPU_INTENSIVE.
The mechanism isn't foolproof:
* Detection depends on tick hitting the work item. Getting preempted at the
right timings may allow a violating work item to evade detection at least
temporarily.
* nohz_full CPUs may not be running ticks and thus can fail detection.
* Even when detection is working, the 10ms detection delays can add up if
many CPU-hogging work items are queued at the same time.
However, in vast majority of cases, this should be able to detect violations
reliably and provide reasonable protection with a small increase in code
complexity.
If some work items trigger this condition repeatedly, the bigger problem
likely is the CPU being saturated with such per-cpu work items and the
solution would be making them UNBOUND. The next patch will add a debug
mechanism to help spot such cases.
v4: Documentation for workqueue.cpu_intensive_thresh_us added to
kernel-parameters.txt.
v3: Switch to use wq_worker_tick() instead of hooking into preemptions as
suggested by Peter.
v2: Lai pointed out that wq_worker_stopping() also needs to be called from
preemption and rtlock paths and an earlier patch was updated
accordingly. This patch adds a comment describing the risk of infinte
recursions and how they're avoided.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
cpuset_can_attach() can fail. Postpone DL BW allocation until all tasks
have been checked. DL BW is not allocated per-task but as a sum over
all DL tasks migrating.
If multiple controllers are attached to the cgroup next to the cpuset
controller a non-cpuset can_attach() can fail. In this case free DL BW
in cpuset_cancel_attach().
Finally, update cpuset DL task count (nr_deadline_tasks) only in
cpuset_attach().
Suggested-by: Waiman Long <longman@redhat.com>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
While moving a set of tasks between exclusive cpusets,
cpuset_can_attach() -> task_can_attach() calls dl_cpu_busy(..., p) for
DL BW overflow checking and per-task DL BW allocation on the destination
root_domain for the DL tasks in this set.
This approach has the issue of not freeing already allocated DL BW in
the following error cases:
(1) The set of tasks includes multiple DL tasks and DL BW overflow
checking fails for one of the subsequent DL tasks.
(2) Another controller next to the cpuset controller which is attached
to the same cgroup fails in its can_attach().
To address this problem rework dl_cpu_busy():
(1) Split it into dl_bw_check_overflow() & dl_bw_alloc() and add a
dedicated dl_bw_free().
(2) dl_bw_alloc() & dl_bw_free() take a `u64 dl_bw` parameter instead of
a `struct task_struct *p` used in dl_cpu_busy(). This allows to
allocate DL BW for a set of tasks too rather than only for a single
task.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Qais reported that iterating over all tasks when rebuilding root domains
for finding out which ones are DEADLINE and need their bandwidth
correctly restored on such root domains can be a costly operation (10+
ms delays on suspend-resume).
To fix the problem keep track of the number of DEADLINE tasks belonging
to each cpuset and then use this information (followup patch) to only
perform the above iteration if DEADLINE tasks are actually present in
the cpuset for which a corresponding root domain is being rebuilt.
Reported-by: Qais Yousef <qyousef@layalina.io>
Link: https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef@layalina.io/
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Turns out percpu_cpuset_rwsem - commit 1243dc518c ("cgroup/cpuset:
Convert cpuset_mutex to percpu_rwsem") - wasn't such a brilliant idea,
as it has been reported to cause slowdowns in workloads that need to
change cpuset configuration frequently and it is also not implementing
priority inheritance (which causes troubles with realtime workloads).
Convert percpu_cpuset_rwsem back to regular cpuset_mutex. Also grab it
only for SCHED_DEADLINE tasks (other policies don't care about stable
cpusets anyway).
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit e6fe3f422b ("sched: Make multiple runqueue task counters
32-bit") changed the type for rq->nr_uninterruptible from "unsigned
long" to "unsigned int", but left wrong cast print to
/sys/kernel/debug/sched/debug and to the console.
For example, nr_uninterruptible's value is fffffff7 with type
"unsigned int", (long)nr_uninterruptible shows 4294967287 while
(int)nr_uninterruptible prints -9. So using int cast fixes wrong
printing.
Signed-off-by: Yan Yan <yanyan.yan@antgroup.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230506074253.44526-1-yanyan.yan@antgroup.com
When a degenerate cluster domain for core with SMT CPUs is removed,
the SD_SHARE_CPUCAPACITY flag in the local child sched group was not
propagated to the new parent. We need this flag to properly determine
whether the local sched group is SMT. Set the flag in the local
child sched group of the new parent sched domain.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Link: https://lkml.kernel.org/r/73cf0959eafa53c02e7ef6bf805d751d9190e55d.1683156492.git.tim.c.chen@linux.intel.com
Current 500ms min window size for psi triggers limits polling interval
to 50ms to prevent polling threads from using too much cpu bandwidth by
polling too frequently. However the number of cgroups with triggers is
unlimited, so this protection can be defeated by creating multiple
cgroups with psi triggers (triggers in each cgroup are served by a single
"psimon" kernel thread).
Instead of limiting min polling period, which also limits the latency of
psi events, it's better to limit psi trigger creation to authorized users
only, like we do for system-wide psi triggers (/proc/pressure/* files can
be written only by processes with CAP_SYS_RESOURCE capability). This also
makes access rules for cgroup psi files consistent with system-wide ones.
Add a CAP_SYS_RESOURCE capability check for cgroup psi file writers and
remove the psi window min size limitation.
Suggested-by: Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/all/cover.1676067791.git.quic_sudaraja@quicinc.com/
Do not assume that all the children of a scheduling domain have a given
flag. Check whether it has the SDF_SHARED_CHILD meta flag.
Suggested-by: Ionela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230406203148.19182-9-ricardo.neri-calderon@linux.intel.com
Now that find_busiest_group() triggers load balancing between a fully_
busy SMT2 core and an idle non-SMT core, it is no longer needed to force
balancing via asym_packing. Use asym_packing only as intended: when there
is high-priority CPU that is idle.
After this change, the same logic apply to SMT and non-SMT local groups.
It makes less sense having a separate function to deal specifically with
SMT. Fold the logic in asym_smt_can_pull_tasks() into sched_asym().
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230406203148.19182-8-ricardo.neri-calderon@linux.intel.com
The prefer_sibling setting acts on the busiest group to move excess tasks
to the local group. This should be done as per request of the child of the
busiest group's sched domain, not the local group's.
Using the flags of the child domain of the local group works fortuitously
if both groups have child domains.
There are cases, however, in which the busiest group's sched domain has
child but the local group's does not. Consider, for instance a non-SMT
core (or an SMT core with only one online sibling) doing load balance with
an SMT core at the MC level. SD_PREFER_SIBLING of the busiest group's child
domain will not be honored. We are left with a fully busy SMT core and an
idle non-SMT core.
Suggested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230406203148.19182-7-ricardo.neri-calderon@linux.intel.com
When comparing two fully_busy scheduling groups, keep the current busiest
group if it represents an SMT core. Tasks in such scheduling group share
CPU resources and need more help than tasks in a non-SMT fully_busy group.
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230406203148.19182-6-ricardo.neri-calderon@linux.intel.com
Using asym_packing priorities within an SMT core is straightforward. Just
follow the priorities that hardware indicates.
When balancing load from an SMT core, also consider the idle state of its
siblings. Priorities do not reflect that an SMT core divides its throughput
among all its busy siblings. They only makes sense when exactly one sibling
is busy.
Indicate that active balance is needed if the destination CPU has lower
priority than the source CPU but the latter has busy SMT siblings.
Make find_busiest_queue() not skip higher-priority SMT cores with more than
busy sibling.
Suggested-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230406203148.19182-5-ricardo.neri-calderon@linux.intel.com
Callers of asym_smt_can_pull_tasks() check the idle state of the
destination CPU and its SMT siblings, if any. No extra checks are needed
in such function.
Since SMT cores divide capacity among its siblings, priorities only really
make sense if only one sibling is active. This is true for SMT2, SMT4,
SMT8, etc. Do not use asym_packing load balance for this case. Instead,
let find_busiest_group() handle imbalances.
When balancing non-SMT cores or at higher scheduling domains (e.g.,
between MC scheduling groups), continue using priorities.
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Len Brown <len.brown@intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230406203148.19182-4-ricardo.neri-calderon@linux.intel.com
When balancing load between cores, all the SMT siblings of the destination
CPU, if any, must be idle. Otherwise, pulling new tasks degrades the
throughput of the busy SMT siblings. The overall throughput of the system
remains the same.
When balancing load within an SMT core this consideration is not relevant.
Follow the priorities that hardware indicates.
Suggested-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230406203148.19182-3-ricardo.neri-calderon@linux.intel.com
asym_packing needs this function to determine whether an SMT core is a
suitable destination for load balancing.
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230406203148.19182-2-ricardo.neri-calderon@linux.intel.com
Fix kernel-doc warnings for cid_lock and use_cid_lock.
These comments are not in kernel-doc format.
kernel/sched/core.c:11496: warning: Cannot understand * @cid_lock: Guarantee forward-progress of cid allocation.
on line 11496 - I thought it was a doc line
kernel/sched/core.c:11505: warning: Cannot understand * @use_cid_lock: Select cid allocation behavior: lock-free vs spinlock.
on line 11505 - I thought it was a doc line
Fixes: 223baf9d17 ("sched: Fix performance regression introduced by mm_cid")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230428031111.322-1-rdunlap@infradead.org
- Remove diagnostics and adjust config for CSD lock diagnostics
- Add a generic IPI-sending tracepoint, as currently there's no easy
way to instrument IPI origins: it's arch dependent and for some
major architectures it's not even consistently available.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull SMP cross-CPU function-call updates from Ingo Molnar:
- Remove diagnostics and adjust config for CSD lock diagnostics
- Add a generic IPI-sending tracepoint, as currently there's no easy
way to instrument IPI origins: it's arch dependent and for some major
architectures it's not even consistently available.
* tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
trace,smp: Trace all smp_function_call*() invocations
trace: Add trace_ipi_send_cpu()
sched, smp: Trace smp callback causing an IPI
smp: reword smp call IPI comment
treewide: Trace IPIs sent via smp_send_reschedule()
irq_work: Trace self-IPIs sent via arch_irq_work_raise()
smp: Trace IPIs sent via arch_send_call_function_ipi_mask()
sched, smp: Trace IPIs sent via send_call_function_single_ipi()
trace: Add trace_ipi_send_cpumask()
kernel/smp: Make csdlock_debug= resettable
locking/csd_lock: Remove per-CPU data indirection from CSD lock debugging
locking/csd_lock: Remove added data from CSD lock debugging
locking/csd_lock: Add Kconfig option for csd_debug default
- Allow unprivileged PSI poll()ing
- Fix performance regression introduced by mm_cid
- Improve livepatch stalls by adding livepatch task switching to cond_resched(),
this resolves livepatching busy-loop stalls with certain CPU-bound kthreads.
- Improve sched_move_task() performance on autogroup configs.
- On core-scheduling CPUs, avoid selecting throttled tasks to run
- Misc cleanups, fixes and improvements.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Allow unprivileged PSI poll()ing
- Fix performance regression introduced by mm_cid
- Improve livepatch stalls by adding livepatch task switching to
cond_resched(). This resolves livepatching busy-loop stalls with
certain CPU-bound kthreads
- Improve sched_move_task() performance on autogroup configs
- On core-scheduling CPUs, avoid selecting throttled tasks to run
- Misc cleanups, fixes and improvements
* tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/clock: Fix local_clock() before sched_clock_init()
sched/rt: Fix bad task migration for rt tasks
sched: Fix performance regression introduced by mm_cid
sched/core: Make sched_dynamic_mutex static
sched/psi: Allow unprivileged polling of N*2s period
sched/psi: Extract update_triggers side effect
sched/psi: Rename existing poll members in preparation
sched/psi: Rearrange polling code in preparation
sched/fair: Fix inaccurate tally of ttwu_move_affine
vhost: Fix livepatch timeouts in vhost_worker()
livepatch,sched: Add livepatch task switching to cond_resched()
livepatch: Skip task_call_func() for current task
livepatch: Convert stack entries array to percpu
sched: Interleave cfs bandwidth timers for improved single thread performance at low utilization
sched/core: Reduce cost of sched_move_task when config autogroup
sched/core: Avoid selecting the task that is throttled to run when core-sched enable
sched/topology: Make sched_energy_mutex,update static
- Mark arch_cpu_idle_dead() __noreturn, make all architectures & drivers that did
this inconsistently follow this new, common convention, and fix all the fallout
that objtool can now detect statically.
- Fix/improve the ORC unwinder becoming unreliable due to UNWIND_HINT_EMPTY ambiguity,
split it into UNWIND_HINT_END_OF_STACK and UNWIND_HINT_UNDEFINED to resolve it.
- Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code.
- Generate ORC data for __pfx code
- Add more __noreturn annotations to various kernel startup/shutdown/panic functions.
- Misc improvements & fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
- Mark arch_cpu_idle_dead() __noreturn, make all architectures &
drivers that did this inconsistently follow this new, common
convention, and fix all the fallout that objtool can now detect
statically
- Fix/improve the ORC unwinder becoming unreliable due to
UNWIND_HINT_EMPTY ambiguity, split it into UNWIND_HINT_END_OF_STACK
and UNWIND_HINT_UNDEFINED to resolve it
- Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code
- Generate ORC data for __pfx code
- Add more __noreturn annotations to various kernel startup/shutdown
and panic functions
- Misc improvements & fixes
* tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
x86/hyperv: Mark hv_ghcb_terminate() as noreturn
scsi: message: fusion: Mark mpt_halt_firmware() __noreturn
x86/cpu: Mark {hlt,resume}_play_dead() __noreturn
btrfs: Mark btrfs_assertfail() __noreturn
objtool: Include weak functions in global_noreturns check
cpu: Mark nmi_panic_self_stop() __noreturn
cpu: Mark panic_smp_self_stop() __noreturn
arm64/cpu: Mark cpu_park_loop() and friends __noreturn
x86/head: Mark *_start_kernel() __noreturn
init: Mark start_kernel() __noreturn
init: Mark [arch_call_]rest_init() __noreturn
objtool: Generate ORC data for __pfx code
x86/linkage: Fix padding for typed functions
objtool: Separate prefix code from stack validation code
objtool: Remove superfluous dead_end_function() check
objtool: Add symbol iteration helpers
objtool: Add WARN_INSN()
scripts/objdump-func: Support multiple functions
context_tracking: Fix KCSAN noinstr violation
objtool: Add stackleak instrumentation to uaccess safe list
...
- updates to scripts/gdb from Glenn Washburn
- kexec cleanups from Bjorn Helgaas
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Merge tag 'mm-nonmm-stable-2023-04-27-16-01' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
"Mainly singleton patches all over the place.
Series of note are:
- updates to scripts/gdb from Glenn Washburn
- kexec cleanups from Bjorn Helgaas"
* tag 'mm-nonmm-stable-2023-04-27-16-01' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (50 commits)
mailmap: add entries for Paul Mackerras
libgcc: add forward declarations for generic library routines
mailmap: add entry for Oleksandr
ocfs2: reduce ioctl stack usage
fs/proc: add Kthread flag to /proc/$pid/status
ia64: fix an addr to taddr in huge_pte_offset()
checkpatch: introduce proper bindings license check
epoll: rename global epmutex
scripts/gdb: add GDB convenience functions $lx_dentry_name() and $lx_i_dentry()
scripts/gdb: create linux/vfs.py for VFS related GDB helpers
uapi/linux/const.h: prefer ISO-friendly __typeof__
delayacct: track delays from IRQ/SOFTIRQ
scripts/gdb: timerlist: convert int chunks to str
scripts/gdb: print interrupts
scripts/gdb: raise error with reduced debugging information
scripts/gdb: add a Radix Tree Parser
lib/rbtree: use '+' instead of '|' for setting color.
proc/stat: remove arch_idle_time()
checkpatch: check for misuse of the link tags
checkpatch: allow Closes tags with links
...
switching from a user process to a kernel thread.
- More folio conversions from Kefeng Wang, Zhang Peng and Pankaj Raghav.
- zsmalloc performance improvements from Sergey Senozhatsky.
- Yue Zhao has found and fixed some data race issues around the
alteration of memcg userspace tunables.
- VFS rationalizations from Christoph Hellwig:
- removal of most of the callers of write_one_page().
- make __filemap_get_folio()'s return value more useful
- Luis Chamberlain has changed tmpfs so it no longer requires swap
backing. Use `mount -o noswap'.
- Qi Zheng has made the slab shrinkers operate locklessly, providing
some scalability benefits.
- Keith Busch has improved dmapool's performance, making part of its
operations O(1) rather than O(n).
- Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
permitting userspace to wr-protect anon memory unpopulated ptes.
- Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive rather
than exclusive, and has fixed a bunch of errors which were caused by its
unintuitive meaning.
- Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
which causes minor faults to install a write-protected pte.
- Vlastimil Babka has done some maintenance work on vma_merge():
cleanups to the kernel code and improvements to our userspace test
harness.
- Cleanups to do_fault_around() by Lorenzo Stoakes.
- Mike Rapoport has moved a lot of initialization code out of various
mm/ files and into mm/mm_init.c.
- Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
DRM, but DRM doesn't use it any more.
- Lorenzo has also coverted read_kcore() and vread() to use iterators
and has thereby removed the use of bounce buffers in some cases.
- Lorenzo has also contributed further cleanups of vma_merge().
- Chaitanya Prakash provides some fixes to the mmap selftesting code.
- Matthew Wilcox changes xfs and afs so they no longer take sleeping
locks in ->map_page(), a step towards RCUification of pagefaults.
- Suren Baghdasaryan has improved mmap_lock scalability by switching to
per-VMA locking.
- Frederic Weisbecker has reworked the percpu cache draining so that it
no longer causes latency glitches on cpu isolated workloads.
- Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
logic.
- Liu Shixin has changed zswap's initialization so we no longer waste a
chunk of memory if zswap is not being used.
- Yosry Ahmed has improved the performance of memcg statistics flushing.
- David Stevens has fixed several issues involving khugepaged,
userfaultfd and shmem.
- Christoph Hellwig has provided some cleanup work to zram's IO-related
code paths.
- David Hildenbrand has fixed up some issues in the selftest code's
testing of our pte state changing.
- Pankaj Raghav has made page_endio() unneeded and has removed it.
- Peter Xu contributed some rationalizations of the userfaultfd
selftests.
- Yosry Ahmed has fixed an issue around memcg's page recalim accounting.
- Chaitanya Prakash has fixed some arm-related issues in the
selftests/mm code.
- Longlong Xia has improved the way in which KSM handles hwpoisoned
pages.
- Peter Xu fixes a few issues with uffd-wp at fork() time.
- Stefan Roesch has changed KSM so that it may now be used on a
per-process and per-cgroup basis.
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Merge tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
switching from a user process to a kernel thread.
- More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
Raghav.
- zsmalloc performance improvements from Sergey Senozhatsky.
- Yue Zhao has found and fixed some data race issues around the
alteration of memcg userspace tunables.
- VFS rationalizations from Christoph Hellwig:
- removal of most of the callers of write_one_page()
- make __filemap_get_folio()'s return value more useful
- Luis Chamberlain has changed tmpfs so it no longer requires swap
backing. Use `mount -o noswap'.
- Qi Zheng has made the slab shrinkers operate locklessly, providing
some scalability benefits.
- Keith Busch has improved dmapool's performance, making part of its
operations O(1) rather than O(n).
- Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
permitting userspace to wr-protect anon memory unpopulated ptes.
- Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
rather than exclusive, and has fixed a bunch of errors which were
caused by its unintuitive meaning.
- Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
which causes minor faults to install a write-protected pte.
- Vlastimil Babka has done some maintenance work on vma_merge():
cleanups to the kernel code and improvements to our userspace test
harness.
- Cleanups to do_fault_around() by Lorenzo Stoakes.
- Mike Rapoport has moved a lot of initialization code out of various
mm/ files and into mm/mm_init.c.
- Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
DRM, but DRM doesn't use it any more.
- Lorenzo has also coverted read_kcore() and vread() to use iterators
and has thereby removed the use of bounce buffers in some cases.
- Lorenzo has also contributed further cleanups of vma_merge().
- Chaitanya Prakash provides some fixes to the mmap selftesting code.
- Matthew Wilcox changes xfs and afs so they no longer take sleeping
locks in ->map_page(), a step towards RCUification of pagefaults.
- Suren Baghdasaryan has improved mmap_lock scalability by switching to
per-VMA locking.
- Frederic Weisbecker has reworked the percpu cache draining so that it
no longer causes latency glitches on cpu isolated workloads.
- Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
logic.
- Liu Shixin has changed zswap's initialization so we no longer waste a
chunk of memory if zswap is not being used.
- Yosry Ahmed has improved the performance of memcg statistics
flushing.
- David Stevens has fixed several issues involving khugepaged,
userfaultfd and shmem.
- Christoph Hellwig has provided some cleanup work to zram's IO-related
code paths.
- David Hildenbrand has fixed up some issues in the selftest code's
testing of our pte state changing.
- Pankaj Raghav has made page_endio() unneeded and has removed it.
- Peter Xu contributed some rationalizations of the userfaultfd
selftests.
- Yosry Ahmed has fixed an issue around memcg's page recalim
accounting.
- Chaitanya Prakash has fixed some arm-related issues in the
selftests/mm code.
- Longlong Xia has improved the way in which KSM handles hwpoisoned
pages.
- Peter Xu fixes a few issues with uffd-wp at fork() time.
- Stefan Roesch has changed KSM so that it may now be used on a
per-process and per-cgroup basis.
* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
shmem: restrict noswap option to initial user namespace
mm/khugepaged: fix conflicting mods to collapse_file()
sparse: remove unnecessary 0 values from rc
mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
maple_tree: fix allocation in mas_sparse_area()
mm: do not increment pgfault stats when page fault handler retries
zsmalloc: allow only one active pool compaction context
selftests/mm: add new selftests for KSM
mm: add new KSM process and sysfs knobs
mm: add new api to enable ksm per process
mm: shrinkers: fix debugfs file permissions
mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
migrate_pages_batch: fix statistics for longterm pin retry
userfaultfd: use helper function range_in_vma()
lib/show_mem.c: use for_each_populated_zone() simplify code
mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
fs/buffer: convert create_page_buffers to folio_create_buffers
fs/buffer: add folio_create_empty_buffers helper
...
Here is the large set of driver core changes for 6.4-rc1.
Once again, a busy development cycle, with lots of changes happening in
the driver core in the quest to be able to move "struct bus" and "struct
class" into read-only memory, a task now complete with these changes.
This will make the future rust interactions with the driver core more
"provably correct" as well as providing more obvious lifetime rules for
all busses and classes in the kernel.
The changes required for this did touch many individual classes and
busses as many callbacks were changed to take const * parameters
instead. All of these changes have been submitted to the various
subsystem maintainers, giving them plenty of time to review, and most of
them actually did so.
Other than those changes, included in here are a small set of other
things:
- kobject logging improvements
- cacheinfo improvements and updates
- obligatory fw_devlink updates and fixes
- documentation updates
- device property cleanups and const * changes
- firwmare loader dependency fixes.
All of these have been in linux-next for a while with no reported
problems.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH:
"Here is the large set of driver core changes for 6.4-rc1.
Once again, a busy development cycle, with lots of changes happening
in the driver core in the quest to be able to move "struct bus" and
"struct class" into read-only memory, a task now complete with these
changes.
This will make the future rust interactions with the driver core more
"provably correct" as well as providing more obvious lifetime rules
for all busses and classes in the kernel.
The changes required for this did touch many individual classes and
busses as many callbacks were changed to take const * parameters
instead. All of these changes have been submitted to the various
subsystem maintainers, giving them plenty of time to review, and most
of them actually did so.
Other than those changes, included in here are a small set of other
things:
- kobject logging improvements
- cacheinfo improvements and updates
- obligatory fw_devlink updates and fixes
- documentation updates
- device property cleanups and const * changes
- firwmare loader dependency fixes.
All of these have been in linux-next for a while with no reported
problems"
* tag 'driver-core-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (120 commits)
device property: make device_property functions take const device *
driver core: update comments in device_rename()
driver core: Don't require dynamic_debug for initcall_debug probe timing
firmware_loader: rework crypto dependencies
firmware_loader: Strip off \n from customized path
zram: fix up permission for the hot_add sysfs file
cacheinfo: Add use_arch[|_cache]_info field/function
arch_topology: Remove early cacheinfo error message if -ENOENT
cacheinfo: Check cache properties are present in DT
cacheinfo: Check sib_leaf in cache_leaves_are_shared()
cacheinfo: Allow early level detection when DT/ACPI info is missing/broken
cacheinfo: Add arm64 early level initializer implementation
cacheinfo: Add arch specific early level initializer
tty: make tty_class a static const structure
driver core: class: remove struct class_interface * from callbacks
driver core: class: mark the struct class in struct class_interface constant
driver core: class: make class_register() take a const *
driver core: class: mark class_release() as taking a const *
driver core: remove incorrect comment for device_create*
MIPS: vpe-cmp: remove module owner pointer from struct class usage.
...
Have local_clock() return sched_clock() if sched_clock_init() has not
yet run. sched_clock_cpu() has this check but it was not included in the
new noinstr implementation of local_clock().
The effect can be seen on x86 with CONFIG_PRINTK_TIME enabled, for
instance. scd->clock quickly reaches the value of TICK_NSEC and that
value is returned until sched_clock_init() runs.
dmesg without this patch:
[ 0.000000] kvm-clock: ...
[ 0.000002] kvm-clock: ...
[ 0.000672] clocksource: ...
[ 0.001000] tsc: ...
[ 0.001000] e820: ...
[ 0.001000] e820: ...
...
[ 0.001000] ..TIMER: ...
[ 0.001000] clocksource: ...
[ 0.378956] Calibrating delay loop ...
[ 0.379955] pid_max: ...
dmesg with this patch:
[ 0.000000] kvm-clock: ...
[ 0.000001] kvm-clock: ...
[ 0.000675] clocksource: ...
[ 0.002685] tsc: ...
[ 0.003331] e820: ...
[ 0.004190] e820: ...
...
[ 0.421939] ..TIMER: ...
[ 0.422842] clocksource: ...
[ 0.424582] Calibrating delay loop ...
[ 0.425580] pid_max: ...
Fixes: 776f22913b ("sched/clock: Make local_clock() noinstr")
Signed-off-by: Aaron Thompson <dev@aaront.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230413175012.2201-1-dev@aaront.org
Commit 95158a89dd ("sched,rt: Use the full cpumask for balancing")
allows find_lock_lowest_rq() to pick a task with migration disabled.
The purpose of the commit is to push the current running task on the
CPU that has the migrate_disable() task away.
However, there is a race which allows a migrate_disable() task to be
migrated. Consider:
CPU0 CPU1
push_rt_task
check is_migration_disabled(next_task)
task not running and
migration_disabled == 0
find_lock_lowest_rq(next_task, rq);
_double_lock_balance(this_rq, busiest);
raw_spin_rq_unlock(this_rq);
double_rq_lock(this_rq, busiest);
<<wait for busiest rq>>
<wakeup>
task become running
migrate_disable();
<context out>
deactivate_task(rq, next_task, 0);
set_task_cpu(next_task, lowest_rq->cpu);
WARN_ON_ONCE(is_migration_disabled(p));
Fixes: 95158a89dd ("sched,rt: Use the full cpumask for balancing")
Signed-off-by: Schspa Shi <schspa@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Dwaine Gonyier <dgonyier@redhat.com>
Introduce per-mm/cpu current concurrency id (mm_cid) to fix a PostgreSQL
sysbench regression reported by Aaron Lu.
Keep track of the currently allocated mm_cid for each mm/cpu rather than
freeing them immediately on context switch. This eliminates most atomic
operations when context switching back and forth between threads
belonging to different memory spaces in multi-threaded scenarios (many
processes, each with many threads). The per-mm/per-cpu mm_cid values are
serialized by their respective runqueue locks.
Thread migration is handled by introducing invocation to
sched_mm_cid_migrate_to() (with destination runqueue lock held) in
activate_task() for migrating tasks. If the destination cpu's mm_cid is
unset, and if the source runqueue is not actively using its mm_cid, then
the source cpu's mm_cid is moved to the destination cpu on migration.
Introduce a task-work executed periodically, similarly to NUMA work,
which delays reclaim of cid values when they are unused for a period of
time.
Keep track of the allocation time for each per-cpu cid, and let the task
work clear them when they are observed to be older than
SCHED_MM_CID_PERIOD_NS and unused. This task work also clears all
mm_cids which are greater or equal to the Hamming weight of the mm
cidmask to keep concurrency ids compact.
Because we want to ensure the mm_cid converges towards the smaller
values as migrations happen, the prior optimization that was done when
context switching between threads belonging to the same mm is removed,
because it could delay the lazy release of the destination runqueue
mm_cid after it has been replaced by a migration. Removing this prior
optimization is not an issue performance-wise because the introduced
per-mm/per-cpu mm_cid tracking also covers this more specific case.
Fixes: af7f588d8f ("sched: Introduce per-memory-map concurrency ID")
Reported-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Aaron Lu <aaron.lu@intel.com>
Link: https://lore.kernel.org/lkml/20230327080502.GA570847@ziqianlu-desk2/
Delay accounting does not track the delay of IRQ/SOFTIRQ. While
IRQ/SOFTIRQ could have obvious impact on some workloads productivity, such
as when workloads are running on system which is busy handling network
IRQ/SOFTIRQ.
Get the delay of IRQ/SOFTIRQ could help users to reduce such delay. Such
as setting interrupt affinity or task affinity, using kernel thread for
NAPI etc. This is inspired by "sched/psi: Add PSI_IRQ to track
IRQ/SOFTIRQ pressure"[1]. Also fix some code indent problems of older
code.
And update tools/accounting/getdelays.c:
/ # ./getdelays -p 156 -di
print delayacct stats ON
printing IO accounting
PID 156
CPU count real total virtual total delay total delay average
15 15836008 16218149 275700790 18.380ms
IO count delay total delay average
0 0 0.000ms
SWAP count delay total delay average
0 0 0.000ms
RECLAIM count delay total delay average
0 0 0.000ms
THRASHING count delay total delay average
0 0 0.000ms
COMPACT count delay total delay average
0 0 0.000ms
WPCOPY count delay total delay average
36 7586118 0.211ms
IRQ count delay total delay average
42 929161 0.022ms
[1] commit 52b1364ba0b1("sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure")
Link: https://lkml.kernel.org/r/202304081728353557233@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Cc: wangyong <wang.yong12@zte.com.cn>
Cc: junhua huang <huang.junhua@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The sched_dynamic_mutex is only used within the file. Make it static.
Fixes: e3ff7c609f ("livepatch,sched: Add livepatch task switching to cond_resched()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/oe-kbuild-all/202304062335.tNuUjgsl-lkp@intel.com/
When local group is fully busy but its average load is above system load,
computing the imbalance will overflow and local group is not the best
target for pulling this load.
Fixes: 0b0695f2b3 ("sched/fair: Rework load_balance()")
Reported-by: Tingjia Cao <tjcao980311@gmail.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Tingjia Cao <tjcao980311@gmail.com>
Link: https://lore.kernel.org/lkml/CABcWv9_DAhVBOq2=W=2ypKE9dKM5s2DvoV8-U0+GDwwuKZ89jQ@mail.gmail.com/T/
before: last 6 bits of PID is used as index to store information about
tasks accessing VMA's.
after: hash_32 is used to take of cases where tasks are created over a
period of time, and thus improve collision probability.
Result:
The patch series overall improves autonuma cost.
Kernbench around more than 5% improvement and system time in mmtest
autonuma showed more than 80% improvement
Link: https://lkml.kernel.org/r/d5a9f75513300caed74e5c8570bba9317b963c2b.1677672277.git.raghavendra.kt@amd.com
Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Cc: Bharata B Rao <bharata@amd.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Disha Talreja <dishaa.talreja@amd.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This helps to ensure that only recently accessed PIDs scan the VMAs.
Current implementation: (idea supported by PeterZ)
1. Accessing PID information is maintained in two windows.
access_pids[1] being newest.
2. Reset old access PID info i.e. access_pid[0] every (4 *
sysctl_numa_balancing_scan_delay) interval after initial scan delay
period expires.
The above interval seemed to be experimentally optimum since it avoids
frequent reset of access info as well as helps clearing the old access
info regularly. The reset logic is implemented in scan path.
Link: https://lkml.kernel.org/r/f7a675f66d1442d048b4216b2baf94515012c405.1677672277.git.raghavendra.kt@amd.com
Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
Suggested-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Bharata B Rao <bharata@amd.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Disha Talreja <dishaa.talreja@amd.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
During Numa scanning make sure only relevant vmas of the tasks are
scanned.
Before:
All the tasks of a process participate in scanning the vma even if they
do not access vma in it's lifespan.
Now:
Except cases of first few unconditional scans, if a process do
not touch vma (exluding false positive cases of PID collisions)
tasks no longer scan all vma
Logic used:
1) 6 bits of PID used to mark active bit in vma numab status during
fault to remember PIDs accessing vma. (Thanks Mel)
2) Subsequently in scan path, vma scanning is skipped if current PID
had not accessed vma.
3) First two times we do allow unconditional scan to preserve earlier
behaviour of scanning.
Acknowledgement to Bharata B Rao <bharata@amd.com> for initial patch to
store pid information and Peter Zijlstra <peterz@infradead.org> (Usage of
test and set bit)
Link: https://lkml.kernel.org/r/092f03105c7c1d3450f4636b1ea350407f07640e.1677672277.git.raghavendra.kt@amd.com
Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
Suggested-by: Mel Gorman <mgorman@techsingularity.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Disha Talreja <dishaa.talreja@amd.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pach series "sched/numa: Enhance vma scanning", v3.
The patchset proposes one of the enhancements to numa vma scanning
suggested by Mel. This is continuation of [3].
Reposting the rebased patchset to akpm mm-unstable tree (March 1)
Existing mechanism of scan period involves, scan period derived from
per-thread stats. Process Adaptive autoNUMA [1] proposed to gather NUMA
fault stats at per-process level to capture aplication behaviour better.
During that course of discussion, Mel proposed several ideas to enhance
current numa balancing. One of the suggestion was below
Track what threads access a VMA. The suggestion was to use an unsigned
long pid_mask and use the lower bits to tag approximately what threads
access a VMA. Skip VMAs that did not trap a fault. This would be
approximate because of PID collisions but would reduce scanning of areas
the thread is not interested in. The above suggestion intends not to
penalize threads that has no interest in the vma, thus reduce scanning
overhead.
V3 changes are mostly based on PeterZ comments (details below in changes)
Summary of patchset:
Current patchset implements:
1. Delay the vma scanning logic for newly created VMA's so that
additional overhead of scanning is not incurred for short lived tasks
(implementation by Mel)
2. Store the information of tasks accessing VMA in 2 windows. It is
regularly cleared in (4*sysctl_numa_balancing_scan_delay) interval.
The above time is derived from experimenting (Suggested by PeterZ) to
balance between frequent clearing vs obsolete access data
3. hash_32 used to encode task index accessing VMA information
4. VMA's acess information is used to skip scanning for the tasks
which had not accessed VMA
Changes since V2:
patch1:
- Renaming of structure, macro to function,
- Add explanation to heuristics
- Adding more details from result (PeterZ)
Patch2:
- Usage of test and set bit (PeterZ)
- Move storing access PID info to numa_migrate_prep()
- Add a note on fainess among tasks allowed to scan
(PeterZ)
Patch3:
- Maintain two windows of access PID information
(PeterZ supported implementation and Gave idea to extend
to N if needed)
Patch4:
- Apply hash_32 function to track VMA accessing PIDs (PeterZ)
Changes since RFC V1:
- Include Mel's vma scan delay patch
- Change the accessing pid store logic (Thanks Mel)
- Fencing structure / code to NUMA_BALANCING (David, Mel)
- Adding clearing access PID logic (Mel)
- Descriptive change log ( Mike Rapoport)
Things to ponder over:
==========================================
- Improvement to clearing accessing PIDs logic (discussed in-detail in
patch3 itself (Done in this patchset by implementing 2 window history)
- Current scan period is not changed in the patchset, so we do see
frequent tries to scan. Relaxing scan period dynamically could improve
results further.
[1] sched/numa: Process Adaptive autoNUMA
Link: https://lore.kernel.org/lkml/20220128052851.17162-1-bharata@amd.com/T/
[2] RFC V1 Link:
https://lore.kernel.org/all/cover.1673610485.git.raghavendra.kt@amd.com/
[3] V2 Link:
https://lore.kernel.org/lkml/cover.1675159422.git.raghavendra.kt@amd.com/
Results:
Summary: Huge autonuma cost reduction seen in mmtest. Kernbench improvement
is more than 5% and huge system time (80%+) improvement from mmtest autonuma.
(dbench had huge std deviation to post)
kernbench
===========
6.2.0-mmunstable-base 6.2.0-mmunstable-patched
Amean user-256 22002.51 ( 0.00%) 22649.95 * -2.94%*
Amean syst-256 10162.78 ( 0.00%) 8214.13 * 19.17%*
Amean elsp-256 160.74 ( 0.00%) 156.92 * 2.38%*
Duration User 66017.43 67959.84
Duration System 30503.15 24657.03
Duration Elapsed 504.61 493.12
6.2.0-mmunstable-base 6.2.0-mmunstable-patched
Ops NUMA alloc hit 1738835089.00 1738780310.00
Ops NUMA alloc local 1738834448.00 1738779711.00
Ops NUMA base-page range updates 477310.00 392566.00
Ops NUMA PTE updates 477310.00 392566.00
Ops NUMA hint faults 96817.00 87555.00
Ops NUMA hint local faults % 10150.00 2192.00
Ops NUMA hint local percent 10.48 2.50
Ops NUMA pages migrated 86660.00 85363.00
Ops AutoNUMA cost 489.07 442.14
autonumabench
===============
6.2.0-mmunstable-base 6.2.0-mmunstable-patched
Amean syst-NUMA01 399.50 ( 0.00%) 52.05 * 86.97%*
Amean syst-NUMA01_THREADLOCAL 0.21 ( 0.00%) 0.22 * -5.41%*
Amean syst-NUMA02 0.80 ( 0.00%) 0.78 * 2.68%*
Amean syst-NUMA02_SMT 0.65 ( 0.00%) 0.68 * -3.95%*
Amean elsp-NUMA01 313.26 ( 0.00%) 313.11 * 0.05%*
Amean elsp-NUMA01_THREADLOCAL 1.06 ( 0.00%) 1.08 * -1.76%*
Amean elsp-NUMA02 3.19 ( 0.00%) 3.24 * -1.52%*
Amean elsp-NUMA02_SMT 3.72 ( 0.00%) 3.61 * 2.92%*
Duration User 396433.47 324835.96
Duration System 2808.70 376.66
Duration Elapsed 2258.61 2258.12
6.2.0-mmunstable-base 6.2.0-mmunstable-patched
Ops NUMA alloc hit 59921806.00 49623489.00
Ops NUMA alloc miss 0.00 0.00
Ops NUMA interleave hit 0.00 0.00
Ops NUMA alloc local 59920880.00 49622594.00
Ops NUMA base-page range updates 152259275.00 50075.00
Ops NUMA PTE updates 152259275.00 50075.00
Ops NUMA PMD updates 0.00 0.00
Ops NUMA hint faults 154660352.00 39014.00
Ops NUMA hint local faults % 138550501.00 23139.00
Ops NUMA hint local percent 89.58 59.31
Ops NUMA pages migrated 8179067.00 14147.00
Ops AutoNUMA cost 774522.98 195.69
This patch (of 4):
Currently whenever a new task is created we wait for
sysctl_numa_balancing_scan_delay to avoid unnessary scanning overhead.
Extend the same logic to new or very short-lived VMAs.
[raghavendra.kt@amd.com: add initialization in vm_area_dup())]
Link: https://lkml.kernel.org/r/cover.1677672277.git.raghavendra.kt@amd.com
Link: https://lkml.kernel.org/r/7a6fbba87c8b51e67efd3e74285bb4cb311a16ca.1677672277.git.raghavendra.kt@amd.com
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com>
Cc: Bharata B Rao <bharata@amd.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Disha Talreja <dishaa.talreja@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
PSI offers 2 mechanisms to get information about a specific resource
pressure. One is reading from /proc/pressure/<resource>, which gives
average pressures aggregated every 2s. The other is creating a pollable
fd for a specific resource and cgroup.
The trigger creation requires CAP_SYS_RESOURCE, and gives the
possibility to pick specific time window and threshold, spawing an RT
thread to aggregate the data.
Systemd would like to provide containers the option to monitor pressure
on their own cgroup and sub-cgroups. For example, if systemd launches a
container that itself then launches services, the container should have
the ability to poll() for pressure in individual services. But neither
the container nor the services are privileged.
This patch implements a mechanism to allow unprivileged users to create
pressure triggers. The difference with privileged triggers creation is
that unprivileged ones must have a time window that's a multiple of 2s.
This is so that we can avoid unrestricted spawning of rt threads, and
use instead the same aggregation mechanism done for the averages, which
runs independently of any triggers.
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20230330105418.77061-5-cerasuolodomenico@gmail.com
This change moves update_total flag out of update_triggers function,
currently called only in psi_poll_work.
In the next patch, update_triggers will be called also in psi_avgs_work,
but the total update information is specific to psi_poll_work.
Returning update_total value to the caller let us avoid differentiating
the implementation of update_triggers for different aggregators.
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20230330105418.77061-4-cerasuolodomenico@gmail.com
Renaming in PSI implementation to make a clear distinction between
privileged and unprivileged triggers code to be implemented in the
next patch.
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20230330105418.77061-3-cerasuolodomenico@gmail.com
Move a few functions up in the file to avoid forward declaration needed
in the patch implementing unprivileged PSI triggers.
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20230330105418.77061-2-cerasuolodomenico@gmail.com
There are scenarios where non-affine wakeups are incorrectly counted as
affine wakeups by schedstats.
When wake_affine_idle() returns prev_cpu which doesn't equal to
nr_cpumask_bits, it will slip through the check: target == nr_cpumask_bits
in wake_affine() and be counted as if target == this_cpu in schedstats.
Replace target == nr_cpumask_bits with target != this_cpu to make sure
affine wakeups are accurately tallied.
Fixes: 806486c377 (sched/fair: Do not migrate if the prev_cpu is idle)
Suggested-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Libo Chen <libo.chen@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20220810223313.386614-1-libo.chen@oracle.com
We need the fixes in here for testing, as well as the driver core
changes for documentation updates to build on.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add explicit _lazy_tlb annotated functions for lazy tlb mm refcounting.
This makes the lazy tlb mm references more obvious, and allows the
refcounting scheme to be modified in later changes. There is no
functional change with this patch.
Link: https://lkml.kernel.org/r/20230203071837.1136453-3-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Context
=======
The newly-introduced ipi_send_cpumask tracepoint has a "callback" parameter
which so far has only been fed with NULL.
While CSD_TYPE_SYNC/ASYNC and CSD_TYPE_IRQ_WORK share a similar backing
struct layout (meaning their callback func can be accessed without caring
about the actual CSD type), CSD_TYPE_TTWU doesn't even have a function
attached to its struct. This means we need to check the type of a CSD
before eventually dereferencing its associated callback.
This isn't as trivial as it sounds: the CSD type is stored in
__call_single_node.u_flags, which get cleared right before the callback is
executed via csd_unlock(). This implies checking the CSD type before it is
enqueued on the call_single_queue, as the target CPU's queue can be flushed
before we get to sending an IPI.
Furthermore, send_call_function_single_ipi() only has a CPU parameter, and
would need to have an additional argument to trickle down the invoked
function. This is somewhat silly, as the extra argument will always be
pushed down to the function even when nothing is being traced, which is
unnecessary overhead.
Changes
=======
send_call_function_single_ipi() is only used by smp.c, and is defined in
sched/core.c as it contains scheduler-specific ops (set_nr_if_polling() of
a CPU's idle task).
Split it into two parts: the scheduler bits remain in sched/core.c, and the
actual IPI emission is moved into smp.c. This lets us define an
__always_inline helper function that can take the related callback as
parameter without creating useless register pressure in the non-traced path
which only gains a (disabled) static branch.
Do the same thing for the multi IPI case.
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230307143558.294354-8-vschneid@redhat.com
send_call_function_single_ipi() is the thing that sends IPIs at the bottom
of smp_call_function*() via either generic_exec_single() or
smp_call_function_many_cond(). Give it an IPI-related tracepoint.
Note that this ends up tracing any IPI sent via __smp_call_single_queue(),
which covers __ttwu_queue_wakelist() and irq_work_queue_on() "for free".
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230307143558.294354-3-vschneid@redhat.com
CPU cfs bandwidth controller uses hrtimer. Currently there is no initial
value set. Hence all period timers would align at expiry.
This happens when there are multiple CPU cgroup's.
There is a performance gain that can be achieved here if the timers are
interleaved when the utilization of each CPU cgroup is low and total
utilization of all the CPU cgroup's is less than 50%. If the timers are
interleaved, then the unthrottled cgroup can run freely without many
context switches and can also benefit from SMT Folding. This effect will
be further amplified in SPLPAR environment.
This commit adds a random offset after initializing each hrtimer. This
would result in interleaving the timers at expiry, which helps in achieving
the said performance gain.
This was tested on powerpc platform with 8 core SMT=8. Socket power was
measured when the workload. Benchmarked the stress-ng with power
information. Throughput oriented benchmarks show significant gain up to
25% while power consumption increases up to 15%.
Workload: stress-ng --cpu=32 --cpu-ops=50000.
1CG - 1 cgroup is running.
2CG - 2 cgroups are running together.
Time taken to complete stress-ng in seconds and power is in watts.
each cgroup is throttled at 25% with 100ms as the period value.
6.2-rc6 | with patch
8 core 1CG power 2CG power | 1CG power 2 CG power
27.5 80.6 40 90 | 27.3 82 32.3 104
27.5 81 40.2 91 | 27.5 81 38.7 96
27.7 80 40.1 89 | 27.6 80 29.7 106
27.7 80.1 40.3 94 | 27.6 80 31.5 105
Latency might be affected by this change. That could happen if the CPU was
in a deep idle state which is possible if we interleave the timers. Used
schbench for measuring the latency. Each cgroup is throttled at 25% with
period value is set to 100ms. Numbers are when both the cgroups are
running simultaneously. Latency values don't degrade much. Some
improvement is seen in tail latencies.
6.2-rc6 with patch
Groups: 16
50.0th: 39.5 42.5
75.0th: 924.0 922.0
90.0th: 972.0 968.0
95.0th: 1005.5 994.0
99.0th: 4166.0 2287.0
99.5th: 7314.0 7448.0
99.9th: 15024.0 13600.0
Groups: 32
50.0th: 819.0 463.0
75.0th: 1596.0 918.0
90.0th: 5992.0 1281.5
95.0th: 13184.0 2765.0
99.0th: 21792.0 14240.0
99.5th: 25696.0 18920.0
99.9th: 33280.0 35776.0
Groups: 64
50.0th: 4806.0 3440.0
75.0th: 31136.0 33664.0
90.0th: 54144.0 58752.0
95.0th: 66176.0 67200.0
99.0th: 84736.0 91520.0
99.5th: 97408.0 114048.0
99.9th: 136448.0 140032.0
Initial RFC PATCH, discussions and details on the problem:
Link1: https://lore.kernel.org/lkml/5ae3cb09-8c9a-11e8-75a7-cc774d9bc283@linux.vnet.ibm.com/
Link2: https://lore.kernel.org/lkml/9c57c92c-3e0c-b8c5-4be9-8f4df344a347@linux.vnet.ibm.com/
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Shrikanth Hegde<sshegde@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230223185153.1499710-1-sshegde@linux.vnet.ibm.com
Some sched_move_task calls are useless because that
task_struct->sched_task_group maybe not changed (equals task_group
of cpu_cgroup) when system enable autogroup. So do some checks in
sched_move_task.
sched_move_task eg:
task A belongs to cpu_cgroup0 and autogroup0, it will always belong
to cpu_cgroup0 when do_exit. So there is no need to do {de|en}queue.
The call graph is as follow.
do_exit
sched_autogroup_exit_task
sched_move_task
dequeue_task
sched_change_group
A.sched_task_group = sched_get_task_group (=cpu_cgroup0)
enqueue_task
Performance results:
===========================
1. env
cpu: bogomips=4600.00
kernel: 6.3.0-rc3
cpu_cgroup: 6:cpu,cpuacct:/user.slice
2. cmds
do_exit script:
for i in {0..10000}; do
sleep 0 &
done
wait
Run the above script, then use the following bpftrace cmd to get
the cost of sched_move_task:
bpftrace -e 'k:sched_move_task { @ts[tid] = nsecs; }
kr:sched_move_task /@ts[tid]/
{ @ns += nsecs - @ts[tid]; delete(@ts[tid]); }'
3. cost time(ns):
without patch: 43528033
with patch: 18541416
diff:-24986617 -57.4%
As the result show, the patch will save 57.4% in the scenario.
Signed-off-by: wuchi <wuchi.zero@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230321064459.39421-1-wuchi.zero@gmail.com
When {rt, cfs}_rq or dl task is throttled, since cookied tasks
are not dequeued from the core tree, So sched_core_find() and
sched_core_next() may return throttled task, which may
cause throttled task to run on the CPU.
So we add checks in sched_core_find() and sched_core_next()
to make sure that the return is a runnable task that is
not throttled.
Co-developed-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230316081806.69544-1-jiahao.os@bytedance.com
smatch reports
kernel/sched/topology.c:212:1: warning:
symbol 'sched_energy_mutex' was not declared. Should it be static?
kernel/sched/topology.c:213:6: warning:
symbol 'sched_energy_update' was not declared. Should it be static?
These variables are only used in topology.c, so should be static
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20230314144818.1453523-1-trix@redhat.com
Commit 829c1651e9 ("sched/fair: sanitize vruntime of entity being placed")
fixes an overflowing bug, but ignore a case that se->exec_start is reset
after a migration.
For fixing this case, we delay the reset of se->exec_start after
placing the entity which se->exec_start to detect long sleeping task.
In order to take into account a possible divergence between the clock_task
of 2 rqs, we increase the threshold to around 104 days.
Fixes: 829c1651e9 ("sched/fair: sanitize vruntime of entity being placed")
Originally-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Qiao <zhangqiao22@huawei.com>
Link: https://lore.kernel.org/r/20230317160810.107988-1-vincent.guittot@linaro.org
The debug files under sched/domains can take a long time to regenerate,
especially when updates are done one at a time. Move these files under
the sched verbose debug flag. Allow changes to verbose to trigger
generation of the files. This lets a user batch the updates but still
have the information available. The detailed topology printk messages
are also under verbose.
Discussion that lead to this approach can be found in the link below.
Simplified code to maintain use of debugfs bool routines suggested by
Michael Ellerman <mpe@ellerman.id.au>.
Signed-off-by: Phil Auld <pauld@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Vishal Chourasia <vishalc@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vishal Chourasia <vishalc@linux.vnet.ibm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/all/Y01UWQL2y2r69sBX@li-05afa54c-330e-11b2-a85c-e3f3aa0db1e9.ibm.com/
Link: https://lore.kernel.org/r/20230303183754.3076321-1-pauld@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The getaffinity() system call uses 'cpumask_size()' to decide how big
the CPU mask is - so far so good. It is indeed the allocation size of a
cpumask.
But the code also assumes that the whole allocation is initialized
without actually doing so itself. That's wrong, because we might have
fixed-size allocations (making copying and clearing more efficient), but
not all of it is then necessarily used if 'nr_cpu_ids' is smaller.
Having checked other users of 'cpumask_size()', they all seem to be ok,
either using it purely for the allocation size, or explicitly zeroing
the cpumask before using the size in bytes to copy it.
See for example the ublk_ctrl_get_queue_affinity() function that uses
the proper 'zalloc_cpumask_var()' to make sure that the whole mask is
cleared, whether the storage is on the stack or if it was an external
allocation.
Fix this by just zeroing the allocation before using it. Do the same
for the compat version of sched_getaffinity(), which had the same logic.
Also, for consistency, make sched_getaffinity() use 'cpumask_bits()' to
access the bits. For a cpumask_var_t, it ends up being a pointer to the
same data either way, but it's just a good idea to treat it like you
would a 'cpumask_t'. The compat case already did that.
Reported-by: Ryan Roberts <ryan.roberts@arm.com>
Link: https://lore.kernel.org/lkml/7d026744-6bd6-6827-0471-b5e8eae0be3f@arm.com/
Cc: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Before commit 076cbf5d2163 ("x86/xen: don't let xen_pv_play_dead()
return"), in Xen, when a previously offlined CPU was brought back
online, it unexpectedly resumed execution where it left off in the
middle of the idle loop.
There were some hacks to make that work, but the behavior was surprising
as do_idle() doesn't expect an offlined CPU to return from the dead (in
arch_cpu_idle_dead()).
Now that Xen has been fixed, and the arch-specific implementations of
arch_cpu_idle_dead() also don't return, give it a __noreturn attribute.
This will cause the compiler to complain if an arch-specific
implementation might return. It also improves code generation for both
caller and callee.
Also fixes the following warning:
vmlinux.o: warning: objtool: do_idle+0x25f: unreachable instruction
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/60d527353da8c99d4cf13b6473131d46719ed16d.1676358308.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
- Fix error handling in the apple-soc cpufreq driver (Dan Carpenter).
- Change the log level of a message in the amd-pstate cpufreq driver
so it is more visible to users (Kai-Heng Feng).
- Adjust the balance_performance EPP value for Sapphire Rapids in the
intel_pstate cpufreq driver (Srinivas Pandruvada).
- Remove MODULE_LICENSE from 3 pieces of non-modular code (Nick Alcock).
- Make a read-only kobj_type structure in the schedutil cpufreq governor
constant (Thomas Weißschuh).
- Add Add Power Limit4 support for Meteor Lake SoC to the Intel RAPL
power capping driver (Sumeet Pawnikar).
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Merge tag 'pm-6.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management updates from Rafael Wysocki:
"These update power capping (new hardware support and cleanup) and
cpufreq (bug fixes, cleanups and intel_pstate adjustment for a new
platform).
Specifics:
- Fix error handling in the apple-soc cpufreq driver (Dan Carpenter)
- Change the log level of a message in the amd-pstate cpufreq driver
so it is more visible to users (Kai-Heng Feng)
- Adjust the balance_performance EPP value for Sapphire Rapids in the
intel_pstate cpufreq driver (Srinivas Pandruvada)
- Remove MODULE_LICENSE from 3 pieces of non-modular code (Nick
Alcock)
- Make a read-only kobj_type structure in the schedutil cpufreq
governor constant (Thomas Weißschuh)
- Add Add Power Limit4 support for Meteor Lake SoC to the Intel RAPL
power capping driver (Sumeet Pawnikar)"
* tag 'pm-6.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpufreq: apple-soc: Fix an IS_ERR() vs NULL check
powercap: remove MODULE_LICENSE in non-modules
cpufreq: intel_pstate: remove MODULE_LICENSE in non-modules
powercap: RAPL: Add Power Limit4 support for Meteor Lake SoC
cpufreq: amd-pstate: remove MODULE_LICENSE in non-modules
cpufreq: schedutil: make kobj_type structure constant
cpufreq: amd-pstate: Let user know amd-pstate is disabled
cpufreq: intel_pstate: Adjust balance_performance EPP for Sapphire Rapids
F_SEAL_EXEC") which permits the setting of the memfd execute bit at
memfd creation time, with the option of sealing the state of the X bit.
- Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset()
thread-safe for pmd unshare") which addresses a rare race condition
related to PMD unsharing.
- Several folioification patch serieses from Matthew Wilcox, Vishal
Moola, Sidhartha Kumar and Lorenzo Stoakes
- Johannes Weiner has a series ("mm: push down lock_page_memcg()") which
does perform some memcg maintenance and cleanup work.
- SeongJae Park has added DAMOS filtering to DAMON, with the series
"mm/damon/core: implement damos filter". These filters provide users
with finer-grained control over DAMOS's actions. SeongJae has also done
some DAMON cleanup work.
- Kairui Song adds a series ("Clean up and fixes for swap").
- Vernon Yang contributed the series "Clean up and refinement for maple
tree".
- Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It
adds to MGLRU an LRU of memcgs, to improve the scalability of global
reclaim.
- David Hildenbrand has added some userfaultfd cleanup work in the
series "mm: uffd-wp + change_protection() cleanups".
- Christoph Hellwig has removed the generic_writepages() library
function in the series "remove generic_writepages".
- Baolin Wang has performed some maintenance on the compaction code in
his series "Some small improvements for compaction".
- Sidhartha Kumar is doing some maintenance work on struct page in his
series "Get rid of tail page fields".
- David Hildenbrand contributed some cleanup, bugfixing and
generalization of pte management and of pte debugging in his series "mm:
support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with swap
PTEs".
- Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation
flag in the series "Discard __GFP_ATOMIC".
- Sergey Senozhatsky has improved zsmalloc's memory utilization with his
series "zsmalloc: make zspage chain size configurable".
- Joey Gouly has added prctl() support for prohibiting the creation of
writeable+executable mappings. The previous BPF-based approach had
shortcomings. See "mm: In-kernel support for memory-deny-write-execute
(MDWE)".
- Waiman Long did some kmemleak cleanup and bugfixing in the series
"mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF".
- T.J. Alumbaugh has contributed some MGLRU cleanup work in his series
"mm: multi-gen LRU: improve".
- Jiaqi Yan has provided some enhancements to our memory error
statistics reporting, mainly by presenting the statistics on a per-node
basis. See the series "Introduce per NUMA node memory error
statistics".
- Mel Gorman has a second and hopefully final shot at fixing a CPU-hog
regression in compaction via his series "Fix excessive CPU usage during
compaction".
- Christoph Hellwig does some vmalloc maintenance work in the series
"cleanup vfree and vunmap".
- Christoph Hellwig has removed block_device_operations.rw_page() in ths
series "remove ->rw_page".
- We get some maple_tree improvements and cleanups in Liam Howlett's
series "VMA tree type safety and remove __vma_adjust()".
- Suren Baghdasaryan has done some work on the maintainability of our
vm_flags handling in the series "introduce vm_flags modifier functions".
- Some pagemap cleanup and generalization work in Mike Rapoport's series
"mm, arch: add generic implementation of pfn_valid() for FLATMEM" and
"fixups for generic implementation of pfn_valid()"
- Baoquan He has done some work to make /proc/vmallocinfo and
/proc/kcore better represent the real state of things in his series
"mm/vmalloc.c: allow vread() to read out vm_map_ram areas".
- Jason Gunthorpe rationalized the GUP system's interface to the rest of
the kernel in the series "Simplify the external interface for GUP".
- SeongJae Park wishes to migrate people from DAMON's debugfs interface
over to its sysfs interface. To support this, we'll temporarily be
printing warnings when people use the debugfs interface. See the series
"mm/damon: deprecate DAMON debugfs interface".
- Andrey Konovalov provided the accurately named "lib/stackdepot: fixes
and clean-ups" series.
- Huang Ying has provided a dramatic reduction in migration's TLB flush
IPI rates with the series "migrate_pages(): batch TLB flushing".
- Arnd Bergmann has some objtool fixups in "objtool warning fixes".
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Merge tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Daniel Verkamp has contributed a memfd series ("mm/memfd: add
F_SEAL_EXEC") which permits the setting of the memfd execute bit at
memfd creation time, with the option of sealing the state of the X
bit.
- Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset()
thread-safe for pmd unshare") which addresses a rare race condition
related to PMD unsharing.
- Several folioification patch serieses from Matthew Wilcox, Vishal
Moola, Sidhartha Kumar and Lorenzo Stoakes
- Johannes Weiner has a series ("mm: push down lock_page_memcg()")
which does perform some memcg maintenance and cleanup work.
- SeongJae Park has added DAMOS filtering to DAMON, with the series
"mm/damon/core: implement damos filter".
These filters provide users with finer-grained control over DAMOS's
actions. SeongJae has also done some DAMON cleanup work.
- Kairui Song adds a series ("Clean up and fixes for swap").
- Vernon Yang contributed the series "Clean up and refinement for maple
tree".
- Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It
adds to MGLRU an LRU of memcgs, to improve the scalability of global
reclaim.
- David Hildenbrand has added some userfaultfd cleanup work in the
series "mm: uffd-wp + change_protection() cleanups".
- Christoph Hellwig has removed the generic_writepages() library
function in the series "remove generic_writepages".
- Baolin Wang has performed some maintenance on the compaction code in
his series "Some small improvements for compaction".
- Sidhartha Kumar is doing some maintenance work on struct page in his
series "Get rid of tail page fields".
- David Hildenbrand contributed some cleanup, bugfixing and
generalization of pte management and of pte debugging in his series
"mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with
swap PTEs".
- Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation
flag in the series "Discard __GFP_ATOMIC".
- Sergey Senozhatsky has improved zsmalloc's memory utilization with
his series "zsmalloc: make zspage chain size configurable".
- Joey Gouly has added prctl() support for prohibiting the creation of
writeable+executable mappings.
The previous BPF-based approach had shortcomings. See "mm: In-kernel
support for memory-deny-write-execute (MDWE)".
- Waiman Long did some kmemleak cleanup and bugfixing in the series
"mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF".
- T.J. Alumbaugh has contributed some MGLRU cleanup work in his series
"mm: multi-gen LRU: improve".
- Jiaqi Yan has provided some enhancements to our memory error
statistics reporting, mainly by presenting the statistics on a
per-node basis. See the series "Introduce per NUMA node memory error
statistics".
- Mel Gorman has a second and hopefully final shot at fixing a CPU-hog
regression in compaction via his series "Fix excessive CPU usage
during compaction".
- Christoph Hellwig does some vmalloc maintenance work in the series
"cleanup vfree and vunmap".
- Christoph Hellwig has removed block_device_operations.rw_page() in
ths series "remove ->rw_page".
- We get some maple_tree improvements and cleanups in Liam Howlett's
series "VMA tree type safety and remove __vma_adjust()".
- Suren Baghdasaryan has done some work on the maintainability of our
vm_flags handling in the series "introduce vm_flags modifier
functions".
- Some pagemap cleanup and generalization work in Mike Rapoport's
series "mm, arch: add generic implementation of pfn_valid() for
FLATMEM" and "fixups for generic implementation of pfn_valid()"
- Baoquan He has done some work to make /proc/vmallocinfo and
/proc/kcore better represent the real state of things in his series
"mm/vmalloc.c: allow vread() to read out vm_map_ram areas".
- Jason Gunthorpe rationalized the GUP system's interface to the rest
of the kernel in the series "Simplify the external interface for
GUP".
- SeongJae Park wishes to migrate people from DAMON's debugfs interface
over to its sysfs interface. To support this, we'll temporarily be
printing warnings when people use the debugfs interface. See the
series "mm/damon: deprecate DAMON debugfs interface".
- Andrey Konovalov provided the accurately named "lib/stackdepot: fixes
and clean-ups" series.
- Huang Ying has provided a dramatic reduction in migration's TLB flush
IPI rates with the series "migrate_pages(): batch TLB flushing".
- Arnd Bergmann has some objtool fixups in "objtool warning fixes".
* tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (505 commits)
include/linux/migrate.h: remove unneeded externs
mm/memory_hotplug: cleanup return value handing in do_migrate_range()
mm/uffd: fix comment in handling pte markers
mm: change to return bool for isolate_movable_page()
mm: hugetlb: change to return bool for isolate_hugetlb()
mm: change to return bool for isolate_lru_page()
mm: change to return bool for folio_isolate_lru()
objtool: add UACCESS exceptions for __tsan_volatile_read/write
kmsan: disable ftrace in kmsan core code
kasan: mark addr_has_metadata __always_inline
mm: memcontrol: rename memcg_kmem_enabled()
sh: initialize max_mapnr
m68k/nommu: add missing definition of ARCH_PFN_OFFSET
mm: percpu: fix incorrect size in pcpu_obj_full_size()
maple_tree: reduce stack usage with gcc-9 and earlier
mm: page_alloc: call panic() when memoryless node allocation fails
mm: multi-gen LRU: avoid futile retries
migrate_pages: move THP/hugetlb migration support check to simplify code
migrate_pages: batch flushing TLB
migrate_pages: share more code between _unmap and _move
...
Since commit ee6d3dd4ed ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.
Take advantage of this to constify the structure definition to prevent
modification at runtime.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Core
----
- Add dedicated kmem_cache for typical/small skb->head, avoid having
to access struct page at kfree time, and improve memory use.
- Introduce sysctl to set default RPS configuration for new netdevs.
- Define Netlink protocol specification format which can be used
to describe messages used by each family and auto-generate parsers.
Add tools for generating kernel data structures and uAPI headers.
- Expose all net/core sysctls inside netns.
- Remove 4s sleep in netpoll if carrier is instantly detected on boot.
- Add configurable limit of MDB entries per port, and port-vlan.
- Continue populating drop reasons throughout the stack.
- Retire a handful of legacy Qdiscs and classifiers.
Protocols
---------
- Support IPv4 big TCP (TSO frames larger than 64kB).
- Add IP_LOCAL_PORT_RANGE socket option, to control local port range
on socket by socket basis.
- Track and report in procfs number of MPTCP sockets used.
- Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP
path manager.
- IPv6: don't check net.ipv6.route.max_size and rely on garbage
collection to free memory (similarly to IPv4).
- Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).
- ICMP: add per-rate limit counters.
- Add support for user scanning requests in ieee802154.
- Remove static WEP support.
- Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
reporting.
- WiFi 7 EHT channel puncturing support (client & AP).
BPF
---
- Add a rbtree data structure following the "next-gen data structure"
precedent set by recently added linked list, that is, by using
kfunc + kptr instead of adding a new BPF map type.
- Expose XDP hints via kfuncs with initial support for RX hash and
timestamp metadata.
- Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key
to better support decap on GRE tunnel devices not operating
in collect metadata.
- Improve x86 JIT's codegen for PROBE_MEM runtime error checks.
- Remove the need for trace_printk_lock for bpf_trace_printk
and bpf_trace_vprintk helpers.
- Extend libbpf's bpf_tracing.h support for tracing arguments of
kprobes/uprobes and syscall as a special case.
- Significantly reduce the search time for module symbols
by livepatch and BPF.
- Enable cpumasks to be used as kptrs, which is useful for tracing
programs tracking which tasks end up running on which CPUs in
different time intervals.
- Add support for BPF trampoline on s390x and riscv64.
- Add capability to export the XDP features supported by the NIC.
- Add __bpf_kfunc tag for marking kernel functions as kfuncs.
- Add cgroup.memory=nobpf kernel parameter option to disable BPF
memory accounting for container environments.
Netfilter
---------
- Remove the CLUSTERIP target. It has been marked as obsolete
for years, and we still have WARN splats wrt. races of
the out-of-band /proc interface installed by this target.
- Add 'destroy' commands to nf_tables. They are identical to
the existing 'delete' commands, but do not return an error if
the referenced object (set, chain, rule...) did not exist.
Driver API
----------
- Improve cpumask_local_spread() locality to help NICs set the right
IRQ affinity on AMD platforms.
- Separate C22 and C45 MDIO bus transactions more clearly.
- Introduce new DCB table to control DSCP rewrite on egress.
- Support configuration of Physical Layer Collision Avoidance (PLCA)
Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
shared medium Ethernet.
- Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
preemption of low priority frames by high priority frames.
- Add support for controlling MACSec offload using netlink SET.
- Rework devlink instance refcounts to allow registration and
de-registration under the instance lock. Split the code into multiple
files, drop some of the unnecessarily granular locks and factor out
common parts of netlink operation handling.
- Add TX frame aggregation parameters (for USB drivers).
- Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
messages with notifications for debug.
- Allow offloading of UDP NEW connections via act_ct.
- Add support for per action HW stats in TC.
- Support hardware miss to TC action (continue processing in SW from
a specific point in the action chain).
- Warn if old Wireless Extension user space interface is used with
modern cfg80211/mac80211 drivers. Do not support Wireless Extensions
for Wi-Fi 7 devices at all. Everyone should switch to using nl80211
interface instead.
- Improve the CAN bit timing configuration. Use extack to return error
messages directly to user space, update the SJW handling, including
the definition of a new default value that will benefit CAN-FD
controllers, by increasing their oscillator tolerance.
New hardware / drivers
----------------------
- Ethernet:
- nVidia BlueField-3 support (control traffic driver)
- Ethernet support for imx93 SoCs
- Motorcomm yt8531 gigabit Ethernet PHY
- onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
- Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
- Amlogic gxl MDIO mux
- WiFi:
- RealTek RTL8188EU (rtl8xxxu)
- Qualcomm Wi-Fi 7 devices (ath12k)
- CAN:
- Renesas R-Car V4H
Drivers
-------
- Bluetooth:
- Set Per Platform Antenna Gain (PPAG) for Intel controllers.
- Ethernet NICs:
- Intel (1G, igc):
- support TSN / Qbv / packet scheduling features of i226 model
- Intel (100G, ice):
- use GNSS subsystem instead of TTY
- multi-buffer XDP support
- extend support for GPIO pins to E823 devices
- nVidia/Mellanox:
- update the shared buffer configuration on PFC commands
- implement PTP adjphase function for HW offset control
- TC support for Geneve and GRE with VF tunnel offload
- more efficient crypto key management method
- multi-port eswitch support
- Netronome/Corigine:
- add DCB IEEE support
- support IPsec offloading for NFP3800
- Freescale/NXP (enetc):
- enetc: support XDP_REDIRECT for XDP non-linear buffers
- enetc: improve reconfig, avoid link flap and waiting for idle
- enetc: support MAC Merge layer
- Other NICs:
- sfc/ef100: add basic devlink support for ef100
- ionic: rx_push mode operation (writing descriptors via MMIO)
- bnxt: use the auxiliary bus abstraction for RDMA
- r8169: disable ASPM and reset bus in case of tx timeout
- cpsw: support QSGMII mode for J721e CPSW9G
- cpts: support pulse-per-second output
- ngbe: add an mdio bus driver
- usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
- r8152: handle devices with FW with NCM support
- amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
- virtio-net: support multi buffer XDP
- virtio/vsock: replace virtio_vsock_pkt with sk_buff
- tsnep: XDP support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add support for latency TLV (in FW control messages)
- Microchip (sparx5):
- separate explicit and implicit traffic forwarding rules, make
the implicit rules always active
- add support for egress DSCP rewrite
- IS0 VCAP support (Ingress Classification)
- IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.)
- ES2 VCAP support (Egress Access Control)
- support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1)
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- add MAB (port auth) offload support
- enable PTP receive for mv88e6390
- NXP (ocelot):
- support MAC Merge layer
- support for the the vsc7512 internal copper phys
- Microchip:
- lan9303: convert to PHYLINK
- lan966x: support TC flower filter statistics
- lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
- lan937x: support Credit Based Shaper configuration
- ksz9477: support Energy Efficient Ethernet
- other:
- qca8k: convert to regmap read/write API, use bulk operations
- rswitch: Improve TX timestamp accuracy
- Intel WiFi (iwlwifi):
- EHT (Wi-Fi 7) rate reporting
- STEP equalizer support: transfer some STEP (connection to radio
on platforms with integrated wifi) related parameters from the
BIOS to the firmware.
- Qualcomm 802.11ax WiFi (ath11k):
- IPQ5018 support
- Fine Timing Measurement (FTM) responder role support
- channel 177 support
- MediaTek WiFi (mt76):
- per-PHY LED support
- mt7996: EHT (Wi-Fi 7) support
- Wireless Ethernet Dispatch (WED) reset support
- switch to using page pool allocator
- RealTek WiFi (rtw89):
- support new version of Bluetooth co-existance
- Mobile:
- rmnet: support TX aggregation.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
"Core:
- Add dedicated kmem_cache for typical/small skb->head, avoid having
to access struct page at kfree time, and improve memory use.
- Introduce sysctl to set default RPS configuration for new netdevs.
- Define Netlink protocol specification format which can be used to
describe messages used by each family and auto-generate parsers.
Add tools for generating kernel data structures and uAPI headers.
- Expose all net/core sysctls inside netns.
- Remove 4s sleep in netpoll if carrier is instantly detected on
boot.
- Add configurable limit of MDB entries per port, and port-vlan.
- Continue populating drop reasons throughout the stack.
- Retire a handful of legacy Qdiscs and classifiers.
Protocols:
- Support IPv4 big TCP (TSO frames larger than 64kB).
- Add IP_LOCAL_PORT_RANGE socket option, to control local port range
on socket by socket basis.
- Track and report in procfs number of MPTCP sockets used.
- Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
manager.
- IPv6: don't check net.ipv6.route.max_size and rely on garbage
collection to free memory (similarly to IPv4).
- Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).
- ICMP: add per-rate limit counters.
- Add support for user scanning requests in ieee802154.
- Remove static WEP support.
- Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
reporting.
- WiFi 7 EHT channel puncturing support (client & AP).
BPF:
- Add a rbtree data structure following the "next-gen data structure"
precedent set by recently added linked list, that is, by using
kfunc + kptr instead of adding a new BPF map type.
- Expose XDP hints via kfuncs with initial support for RX hash and
timestamp metadata.
- Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
better support decap on GRE tunnel devices not operating in collect
metadata.
- Improve x86 JIT's codegen for PROBE_MEM runtime error checks.
- Remove the need for trace_printk_lock for bpf_trace_printk and
bpf_trace_vprintk helpers.
- Extend libbpf's bpf_tracing.h support for tracing arguments of
kprobes/uprobes and syscall as a special case.
- Significantly reduce the search time for module symbols by
livepatch and BPF.
- Enable cpumasks to be used as kptrs, which is useful for tracing
programs tracking which tasks end up running on which CPUs in
different time intervals.
- Add support for BPF trampoline on s390x and riscv64.
- Add capability to export the XDP features supported by the NIC.
- Add __bpf_kfunc tag for marking kernel functions as kfuncs.
- Add cgroup.memory=nobpf kernel parameter option to disable BPF
memory accounting for container environments.
Netfilter:
- Remove the CLUSTERIP target. It has been marked as obsolete for
years, and we still have WARN splats wrt races of the out-of-band
/proc interface installed by this target.
- Add 'destroy' commands to nf_tables. They are identical to the
existing 'delete' commands, but do not return an error if the
referenced object (set, chain, rule...) did not exist.
Driver API:
- Improve cpumask_local_spread() locality to help NICs set the right
IRQ affinity on AMD platforms.
- Separate C22 and C45 MDIO bus transactions more clearly.
- Introduce new DCB table to control DSCP rewrite on egress.
- Support configuration of Physical Layer Collision Avoidance (PLCA)
Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
shared medium Ethernet.
- Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
preemption of low priority frames by high priority frames.
- Add support for controlling MACSec offload using netlink SET.
- Rework devlink instance refcounts to allow registration and
de-registration under the instance lock. Split the code into
multiple files, drop some of the unnecessarily granular locks and
factor out common parts of netlink operation handling.
- Add TX frame aggregation parameters (for USB drivers).
- Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
messages with notifications for debug.
- Allow offloading of UDP NEW connections via act_ct.
- Add support for per action HW stats in TC.
- Support hardware miss to TC action (continue processing in SW from
a specific point in the action chain).
- Warn if old Wireless Extension user space interface is used with
modern cfg80211/mac80211 drivers. Do not support Wireless
Extensions for Wi-Fi 7 devices at all. Everyone should switch to
using nl80211 interface instead.
- Improve the CAN bit timing configuration. Use extack to return
error messages directly to user space, update the SJW handling,
including the definition of a new default value that will benefit
CAN-FD controllers, by increasing their oscillator tolerance.
New hardware / drivers:
- Ethernet:
- nVidia BlueField-3 support (control traffic driver)
- Ethernet support for imx93 SoCs
- Motorcomm yt8531 gigabit Ethernet PHY
- onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
- Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
- Amlogic gxl MDIO mux
- WiFi:
- RealTek RTL8188EU (rtl8xxxu)
- Qualcomm Wi-Fi 7 devices (ath12k)
- CAN:
- Renesas R-Car V4H
Drivers:
- Bluetooth:
- Set Per Platform Antenna Gain (PPAG) for Intel controllers.
- Ethernet NICs:
- Intel (1G, igc):
- support TSN / Qbv / packet scheduling features of i226 model
- Intel (100G, ice):
- use GNSS subsystem instead of TTY
- multi-buffer XDP support
- extend support for GPIO pins to E823 devices
- nVidia/Mellanox:
- update the shared buffer configuration on PFC commands
- implement PTP adjphase function for HW offset control
- TC support for Geneve and GRE with VF tunnel offload
- more efficient crypto key management method
- multi-port eswitch support
- Netronome/Corigine:
- add DCB IEEE support
- support IPsec offloading for NFP3800
- Freescale/NXP (enetc):
- support XDP_REDIRECT for XDP non-linear buffers
- improve reconfig, avoid link flap and waiting for idle
- support MAC Merge layer
- Other NICs:
- sfc/ef100: add basic devlink support for ef100
- ionic: rx_push mode operation (writing descriptors via MMIO)
- bnxt: use the auxiliary bus abstraction for RDMA
- r8169: disable ASPM and reset bus in case of tx timeout
- cpsw: support QSGMII mode for J721e CPSW9G
- cpts: support pulse-per-second output
- ngbe: add an mdio bus driver
- usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
- r8152: handle devices with FW with NCM support
- amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
- virtio-net: support multi buffer XDP
- virtio/vsock: replace virtio_vsock_pkt with sk_buff
- tsnep: XDP support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add support for latency TLV (in FW control messages)
- Microchip (sparx5):
- separate explicit and implicit traffic forwarding rules, make
the implicit rules always active
- add support for egress DSCP rewrite
- IS0 VCAP support (Ingress Classification)
- IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
etc.)
- ES2 VCAP support (Egress Access Control)
- support for Per-Stream Filtering and Policing (802.1Q,
8.6.5.1)
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- add MAB (port auth) offload support
- enable PTP receive for mv88e6390
- NXP (ocelot):
- support MAC Merge layer
- support for the the vsc7512 internal copper phys
- Microchip:
- lan9303: convert to PHYLINK
- lan966x: support TC flower filter statistics
- lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
- lan937x: support Credit Based Shaper configuration
- ksz9477: support Energy Efficient Ethernet
- other:
- qca8k: convert to regmap read/write API, use bulk operations
- rswitch: Improve TX timestamp accuracy
- Intel WiFi (iwlwifi):
- EHT (Wi-Fi 7) rate reporting
- STEP equalizer support: transfer some STEP (connection to radio
on platforms with integrated wifi) related parameters from the
BIOS to the firmware.
- Qualcomm 802.11ax WiFi (ath11k):
- IPQ5018 support
- Fine Timing Measurement (FTM) responder role support
- channel 177 support
- MediaTek WiFi (mt76):
- per-PHY LED support
- mt7996: EHT (Wi-Fi 7) support
- Wireless Ethernet Dispatch (WED) reset support
- switch to using page pool allocator
- RealTek WiFi (rtw89):
- support new version of Bluetooth co-existance
- Mobile:
- rmnet: support TX aggregation"
* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
page_pool: add a comment explaining the fragment counter usage
net: ethtool: fix __ethtool_dev_mm_supported() implementation
ethtool: pse-pd: Fix double word in comments
xsk: add linux/vmalloc.h to xsk.c
sefltests: netdevsim: wait for devlink instance after netns removal
selftest: fib_tests: Always cleanup before exit
net/mlx5e: Align IPsec ASO result memory to be as required by hardware
net/mlx5e: TC, Set CT miss to the specific ct action instance
net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
net/mlx5: Refactor tc miss handling to a single function
net/mlx5: Kconfig: Make tc offload depend on tc skb extension
net/sched: flower: Support hardware miss to tc action
net/sched: flower: Move filter handle initialization earlier
net/sched: cls_api: Support hardware miss to tc action
net/sched: Rename user cookie and act cookie
sfc: fix builds without CONFIG_RTC_LIB
sfc: clean up some inconsistent indentings
net/mlx4_en: Introduce flexible array to silence overflow warning
net: lan966x: Fix possible deadlock inside PTP
net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
...
This pull request contains the following branches:
doc.2023.01.05a: Documentation updates.
fixes.2023.01.23a: Miscellaneous fixes, perhaps most notably:
o Throttling callback invocation based on the number of callbacks
that are now ready to invoke instead of on the total number
of callbacks.
o Several patches that suppress false-positive boot-time
diagnostics, for example, due to lockdep not yet being
initialized.
o Make expedited RCU CPU stall warnings dump stacks of any tasks
that are blocking the stalled grace period. (Normal RCU CPU
stall warnings have doen this for mnay years.)
o Lazy-callback fixes to avoid delays during boot, suspend, and
resume. (Note that lazy callbacks must be explicitly enabled,
so this should not (yet) affect production use cases.)
kvfree.2023.01.03a: Cause kfree_rcu() and friends to take advantage of
polled grace periods, thus reducing memory footprint by almost
two orders of magnitude, admittedly on a microbenchmark.
This series also begins the transition from kfree_rcu(p) to
kfree_rcu_mightsleep(p). This transition was motivated by bugs
where kfree_rcu(p), which can block, was typed instead of the
intended kfree_rcu(p, rh).
srcu.2023.01.03a: SRCU updates, perhaps most notably fixing a bug that
causes SRCU to fail when booted on a system with a non-zero boot
CPU. This surprising situation actually happens for kdump kernels
on the powerpc architecture. It also adds an srcu_down_read()
and srcu_up_read(), which act like srcu_read_lock() and
srcu_read_unlock(), but allow an SRCU read-side critical section
to be handed off from one task to another.
srcu-always.2023.02.02a: Cleans up the now-useless SRCU Kconfig option.
There are a few more commits that are not yet acked or pulled
into maintainer trees, and these will be in a pull request for
a later merge window.
tasks.2023.01.03a: RCU-tasks updates, perhaps most notably these fixes:
o A strange interaction between PID-namespace unshare and the
RCU-tasks grace period that results in a low-probability but
very real hang.
o A race between an RCU tasks rude grace period on a single-CPU
system and CPU-hotplug addition of the second CPU that can result
in a too-short grace period.
o A race between shrinking RCU tasks down to a single callback list
and queuing a new callback to some other CPU, but where that
queuing is delayed for more than an RCU grace period. This can
result in that callback being stranded on the non-boot CPU.
torture.2023.01.05a: Torture-test updates and fixes.
torturescript.2023.01.03a: Torture-test scripting updates and fixes.
stall.2023.01.09a: Provide additional RCU CPU stall-warning information
in kernels built with CONFIG_RCU_CPU_STALL_CPUTIME=y, and
restore the full five-minute timeout limit for expedited RCU
CPU stall warnings.
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Merge tag 'rcu.2023.02.10a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull RCU updates from Paul McKenney:
- Documentation updates
- Miscellaneous fixes, perhaps most notably:
- Throttling callback invocation based on the number of callbacks
that are now ready to invoke instead of on the total number of
callbacks
- Several patches that suppress false-positive boot-time
diagnostics, for example, due to lockdep not yet being
initialized
- Make expedited RCU CPU stall warnings dump stacks of any tasks
that are blocking the stalled grace period. (Normal RCU CPU
stall warnings have done this for many years)
- Lazy-callback fixes to avoid delays during boot, suspend, and
resume. (Note that lazy callbacks must be explicitly enabled, so
this should not (yet) affect production use cases)
- Make kfree_rcu() and friends take advantage of polled grace periods,
thus reducing memory footprint by almost two orders of magnitude,
admittedly on a microbenchmark
This also begins the transition from kfree_rcu(p) to
kfree_rcu_mightsleep(p). This transition was motivated by bugs where
kfree_rcu(p), which can block, was typed instead of the intended
kfree_rcu(p, rh)
- SRCU updates, perhaps most notably fixing a bug that causes SRCU to
fail when booted on a system with a non-zero boot CPU. This
surprising situation actually happens for kdump kernels on the
powerpc architecture
This also adds an srcu_down_read() and srcu_up_read(), which act like
srcu_read_lock() and srcu_read_unlock(), but allow an SRCU read-side
critical section to be handed off from one task to another
- Clean up the now-useless SRCU Kconfig option
There are a few more commits that are not yet acked or pulled into
maintainer trees, and these will be in a pull request for a later
merge window
- RCU-tasks updates, perhaps most notably these fixes:
- A strange interaction between PID-namespace unshare and the
RCU-tasks grace period that results in a low-probability but
very real hang
- A race between an RCU tasks rude grace period on a single-CPU
system and CPU-hotplug addition of the second CPU that can
result in a too-short grace period
- A race between shrinking RCU tasks down to a single callback
list and queuing a new callback to some other CPU, but where
that queuing is delayed for more than an RCU grace period. This
can result in that callback being stranded on the non-boot CPU
- Torture-test updates and fixes
- Torture-test scripting updates and fixes
- Provide additional RCU CPU stall-warning information in kernels built
with CONFIG_RCU_CPU_STALL_CPUTIME=y, and restore the full five-minute
timeout limit for expedited RCU CPU stall warnings
* tag 'rcu.2023.02.10a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (80 commits)
rcu/kvfree: Add kvfree_rcu_mightsleep() and kfree_rcu_mightsleep()
kernel/notifier: Remove CONFIG_SRCU
init: Remove "select SRCU"
fs/quota: Remove "select SRCU"
fs/notify: Remove "select SRCU"
fs/btrfs: Remove "select SRCU"
fs: Remove CONFIG_SRCU
drivers/pci/controller: Remove "select SRCU"
drivers/net: Remove "select SRCU"
drivers/md: Remove "select SRCU"
drivers/hwtracing/stm: Remove "select SRCU"
drivers/dax: Remove "select SRCU"
drivers/base: Remove CONFIG_SRCU
rcu: Disable laziness if lazy-tracking says so
rcu: Track laziness during boot and suspend
rcu: Remove redundant call to rcu_boost_kthread_setaffinity()
rcu: Allow up to five minutes expedited RCU CPU stall-warning timeouts
rcu: Align the output of RCU CPU stall warning messages
rcu: Add RCU stall diagnosis information
sched: Add helper nr_context_switches_cpu()
...
- Improve the scalability of the CFS bandwidth unthrottling logic
with large number of CPUs.
- Fix & rework various cpuidle routines, simplify interaction with
the generic scheduler code. Add __cpuidle methods as noinstr to
objtool's noinstr detection and fix boatloads of cpuidle bugs & quirks.
- Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS,
to query previously issued registrations.
- Limit scheduler slice duration to the sysctl_sched_latency period,
to improve scheduling granularity with a large number of SCHED_IDLE
tasks.
- Debuggability enhancement on sys_exit(): warn about disabled IRQs,
but also enable them to prevent a cascade of followup problems and
repeat warnings.
- Fix the rescheduling logic in prio_changed_dl().
- Micro-optimize cpufreq and sched-util methods.
- Micro-optimize ttwu_runnable()
- Micro-optimize the idle-scanning in update_numa_stats(),
select_idle_capacity() and steal_cookie_task().
- Update the RSEQ code & self-tests
- Constify various scheduler methods
- Remove unused methods
- Refine __init tags
- Documentation updates
- ... Misc other cleanups, fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Improve the scalability of the CFS bandwidth unthrottling logic with
large number of CPUs.
- Fix & rework various cpuidle routines, simplify interaction with the
generic scheduler code. Add __cpuidle methods as noinstr to objtool's
noinstr detection and fix boatloads of cpuidle bugs & quirks.
- Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS, to query
previously issued registrations.
- Limit scheduler slice duration to the sysctl_sched_latency period, to
improve scheduling granularity with a large number of SCHED_IDLE
tasks.
- Debuggability enhancement on sys_exit(): warn about disabled IRQs,
but also enable them to prevent a cascade of followup problems and
repeat warnings.
- Fix the rescheduling logic in prio_changed_dl().
- Micro-optimize cpufreq and sched-util methods.
- Micro-optimize ttwu_runnable()
- Micro-optimize the idle-scanning in update_numa_stats(),
select_idle_capacity() and steal_cookie_task().
- Update the RSEQ code & self-tests
- Constify various scheduler methods
- Remove unused methods
- Refine __init tags
- Documentation updates
- Misc other cleanups, fixes
* tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (110 commits)
sched/rt: pick_next_rt_entity(): check list_entry
sched/deadline: Add more reschedule cases to prio_changed_dl()
sched/fair: sanitize vruntime of entity being placed
sched/fair: Remove capacity inversion detection
sched/fair: unlink misfit task from cpu overutilized
objtool: mem*() are not uaccess safe
cpuidle: Fix poll_idle() noinstr annotation
sched/clock: Make local_clock() noinstr
sched/clock/x86: Mark sched_clock() noinstr
x86/pvclock: Improve atomic update of last_value in pvclock_clocksource_read()
x86/atomics: Always inline arch_atomic64*()
cpuidle: tracing, preempt: Squash _rcuidle tracing
cpuidle: tracing: Warn about !rcu_is_watching()
cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG
cpuidle: drivers: firmware: psci: Dont instrument suspend code
KVM: selftests: Fix build of rseq test
exit: Detect and fix irq disabled state in oops
cpuidle, arm64: Fix the ARM64 cpuidle logic
cpuidle: mvebu: Fix duplicate flags assignment
sched/fair: Limit sched slice duration
...
Despite that prev_hop is used conditionally on cur_hop
is not the first hop, it's initialized unconditionally.
Because initialization implies dereferencing, it might happen
that the code dereferences uninitialized memory, which has been
spotted by KASAN. Fix it by reorganizing hop_cmp() logic.
Reported-by: Bruno Goncalves <bgoncalv@redhat.com>
Fixes: cd7f55359c ("sched: add sched_numa_find_nth_cpu()")
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Link: https://lore.kernel.org/r/Y+7avK6V9SyAWsXi@yury-laptop/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
If a non-root cgroup gets removed when there is a thread that registered
trigger and is polling on a pressure file within the cgroup, the polling
waitqueue gets freed in the following path:
do_rmdir
cgroup_rmdir
kernfs_drain_open_files
cgroup_file_release
cgroup_pressure_release
psi_trigger_destroy
However, the polling thread still has a reference to the pressure file and
will access the freed waitqueue when the file is closed or upon exit:
fput
ep_eventpoll_release
ep_free
ep_remove_wait_queue
remove_wait_queue
This results in use-after-free as pasted below.
The fundamental problem here is that cgroup_file_release() (and
consequently waitqueue's lifetime) is not tied to the file's real lifetime.
Using wake_up_pollfree() here might be less than ideal, but it is in line
with the comment at commit 42288cb44c ("wait: add wake_up_pollfree()")
since the waitqueue's lifetime is not tied to file's one and can be
considered as another special case. While this would be fixable by somehow
making cgroup_file_release() be tied to the fput(), it would require
sizable refactoring at cgroups or higher layer which might be more
justifiable if we identify more cases like this.
BUG: KASAN: use-after-free in _raw_spin_lock_irqsave+0x60/0xc0
Write of size 4 at addr ffff88810e625328 by task a.out/4404
CPU: 19 PID: 4404 Comm: a.out Not tainted 6.2.0-rc6 #38
Hardware name: Amazon EC2 c5a.8xlarge/, BIOS 1.0 10/16/2017
Call Trace:
<TASK>
dump_stack_lvl+0x73/0xa0
print_report+0x16c/0x4e0
kasan_report+0xc3/0xf0
kasan_check_range+0x2d2/0x310
_raw_spin_lock_irqsave+0x60/0xc0
remove_wait_queue+0x1a/0xa0
ep_free+0x12c/0x170
ep_eventpoll_release+0x26/0x30
__fput+0x202/0x400
task_work_run+0x11d/0x170
do_exit+0x495/0x1130
do_group_exit+0x100/0x100
get_signal+0xd67/0xde0
arch_do_signal_or_restart+0x2a/0x2b0
exit_to_user_mode_prepare+0x94/0x100
syscall_exit_to_user_mode+0x20/0x40
do_syscall_64+0x52/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
</TASK>
Allocated by task 4404:
kasan_set_track+0x3d/0x60
__kasan_kmalloc+0x85/0x90
psi_trigger_create+0x113/0x3e0
pressure_write+0x146/0x2e0
cgroup_file_write+0x11c/0x250
kernfs_fop_write_iter+0x186/0x220
vfs_write+0x3d8/0x5c0
ksys_write+0x90/0x110
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Freed by task 4407:
kasan_set_track+0x3d/0x60
kasan_save_free_info+0x27/0x40
____kasan_slab_free+0x11d/0x170
slab_free_freelist_hook+0x87/0x150
__kmem_cache_free+0xcb/0x180
psi_trigger_destroy+0x2e8/0x310
cgroup_file_release+0x4f/0xb0
kernfs_drain_open_files+0x165/0x1f0
kernfs_drain+0x162/0x1a0
__kernfs_remove+0x1fb/0x310
kernfs_remove_by_name_ns+0x95/0xe0
cgroup_addrm_files+0x67f/0x700
cgroup_destroy_locked+0x283/0x3c0
cgroup_rmdir+0x29/0x100
kernfs_iop_rmdir+0xd1/0x140
vfs_rmdir+0xfe/0x240
do_rmdir+0x13d/0x280
__x64_sys_rmdir+0x2c/0x30
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fixes: 0e94682b73 ("psi: introduce psi monitor")
Signed-off-by: Munehisa Kamata <kamatam@amazon.com>
Signed-off-by: Mengchi Cheng <mengcc@amazon.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/lkml/20230106224859.4123476-1-kamatam@amazon.com/
Link: https://lore.kernel.org/r/20230214212705.4058045-1-kamatam@amazon.com
Since commit 8f9ea86fdf ("sched: Always preserve the user requested
cpumask"), a successful call to sched_setaffinity() should always save
the user requested cpu affinity mask in a task's user_cpus_ptr. However,
when the given cpu mask is the same as the current one, user_cpus_ptr
is not updated. Fix this by saving the user mask in this case too.
Fixes: 8f9ea86fdf ("sched: Always preserve the user requested cpumask")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230203181849.221943-1-longman@redhat.com
Commit 326587b840 ("sched: fix goto retry in pick_next_task_rt()")
removed any path which could make pick_next_rt_entity() return NULL.
However, BUG_ON(!rt_se) in _pick_next_task_rt() (the only caller of
pick_next_rt_entity()) still checks the error condition, which can
never happen, since list_entry() never returns NULL.
Remove the BUG_ON check, and instead emit a warning in the only
possible error condition here: the queue being empty which should
never happen.
Fixes: 326587b840 ("sched: fix goto retry in pick_next_task_rt()")
Signed-off-by: Pietro Borrello <borrello@diag.uniroma1.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20230128-list-entry-null-check-sched-v3-1-b1a71bd1ac6b@diag.uniroma1.it
I've been tracking down an issue on a ~5.17ish kernel where:
CPUx CPUy
<DL task p0 owns an rtmutex M>
<p0 depletes its runtime, gets throttled>
<rq switches to the idle task>
<DL task p1 blocks on M, boost/replenish p0>
<No call to resched_curr() happens here>
[idle task keeps running here until *something*
accidentally sets TIF_NEED_RESCHED]
On that kernel, it is quite easy to trigger using rt-tests's deadline_test
[1] with the test running on isolated CPUs (this reduces the chance of
something unrelated setting TIF_NEED_RESCHED on the idle tasks, making the
issue even more obvious as the hung task detector chimes in).
I haven't been able to reproduce this using a mainline kernel, even if I
revert
2972e3050e ("tracing: Make trace_marker{,_raw} stream-like")
which gets rid of the lock involved in the above test, *but* I cannot
convince myself the issue isn't there from looking at the code.
Make prio_changed_dl() issue a reschedule if the current task isn't a
deadline one. While at it, ensure a reschedule is emitted when a
queued-but-not-current task gets boosted with an earlier deadline that
current's.
[1]: https://git.kernel.org/pub/scm/utils/rt-tests/rt-tests.git
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20230206140612.701871-1-vschneid@redhat.com
When a scheduling entity is placed onto cfs_rq, its vruntime is pulled
to the base level (around cfs_rq->min_vruntime), so that the entity
doesn't gain extra boost when placed backwards.
However, if the entity being placed wasn't executed for a long time, its
vruntime may get too far behind (e.g. while cfs_rq was executing a
low-weight hog), which can inverse the vruntime comparison due to s64
overflow. This results in the entity being placed with its original
vruntime way forwards, so that it will effectively never get to the cpu.
To prevent that, ignore the vruntime of the entity being placed if it
didn't execute for much longer than the characteristic sheduler time
scale.
[rkagan: formatted, adjusted commit log, comments, cutoff value]
Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
Co-developed-by: Roman Kagan <rkagan@amazon.de>
Signed-off-by: Roman Kagan <rkagan@amazon.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230130122216.3555094-1-rkagan@amazon.de
Remove the capacity inversion detection which is now handled by
util_fits_cpu() returning -1 when we need to continue to look for a
potential CPU with better performance.
This ends up almost reverting patches below except for some comments:
commit da07d2f9c1 ("sched/fair: Fixes for capacity inversion detection")
commit aa69c36f31 ("sched/fair: Consider capacity inversion in util_fits_cpu()")
commit 44c7b80bff ("sched/fair: Detect capacity inversion")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230201143628.270912-3-vincent.guittot@linaro.org
By taking into account uclamp_min, the 1:1 relation between task misfit
and cpu overutilized is no more true as a task with a small util_avg may
not fit a high capacity cpu because of uclamp_min constraint.
Add a new state in util_fits_cpu() to reflect the case that task would fit
a CPU except for the uclamp_min hint which is a performance requirement.
Use -1 to reflect that a CPU doesn't fit only because of uclamp_min so we
can use this new value to take additional action to select the best CPU
that doesn't match uclamp_min hint.
When util_fits_cpu() returns -1, we will continue to look for a possible
CPU with better performance, which replaces Capacity Inversion detection
with capacity_orig_of() - thermal_load_avg to detect a capacity inversion.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-and-tested-by: Qais Yousef <qyousef@layalina.io>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Kajetan Puchalski <kajetan.puchalski@arm.com>
Link: https://lore.kernel.org/r/20230201143628.270912-2-vincent.guittot@linaro.org
Use the vma iterator so that the iterator can be invalidated or updated to
avoid each caller doing so.
Link: https://lkml.kernel.org/r/20230120162650.984577-23-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tariq has pointed out that drivers allocating IRQ vectors would benefit
from having smarter NUMA-awareness - cpumask_local_spread() only knows
about the local node and everything outside is in the same bucket.
sched_domains_numa_masks is pretty much what we want to hand out (a cpumask
of CPUs reachable within a given distance budget), introduce
sched_numa_hop_mask() to export those cpumasks.
Link: http://lore.kernel.org/r/20220728191203.4055-1-tariqt@nvidia.com
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The function finds Nth set CPU in a given cpumask starting from a given
node.
Leveraging the fact that each hop in sched_domains_numa_masks includes the
same or greater number of CPUs than the previous one, we can use binary
search on hops instead of linear walk, which makes the overall complexity
of O(log n) in terms of number of cpumask_weight() calls.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Peter Lafreniere <peter@n8pjl.ca>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
With sched_clock() noinstr, provide a noinstr implementation of
local_clock().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126151323.760767043@infradead.org
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Merge tag 'v6.2-rc6' into sched/core, to pick up fixes
Pick up fixes before merging another batch of cpuidle updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The kernel commit 9a5418bc48 ("sched/core: Use kfree_rcu() in
do_set_cpus_allowed()") introduces a bug for kernels built with non-SMP
configs. Calling sched_setaffinity() on such a uniprocessor kernel will
cause cpumask_copy() to be called with a NULL pointer leading to general
protection fault. This is not really a problem in real use cases as
there aren't that many uniprocessor kernel configs in use and calling
sched_setaffinity() on such a uniprocessor system doesn't make sense.
Fix this problem by making sure cpumask_copy() will not be called in
such a case.
Fixes: 9a5418bc48 ("sched/core: Use kfree_rcu() in do_set_cpus_allowed()")
Reported-by: kernel test robot <yujie.liu@intel.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230115193122.563036-1-longman@redhat.com
In presence of a lot of small weight tasks like sched_idle tasks, normal
or high weight tasks can see their ideal runtime (sched_slice) to increase
to hundreds ms whereas it normally stays below sysctl_sched_latency.
2 normal tasks running on a CPU will have a max sched_slice of 12ms
(half of the sched_period). This means that they will make progress
every sysctl_sched_latency period.
If we now add 1000 idle tasks on the CPU, the sched_period becomes
3006 ms and the ideal runtime of the normal tasks becomes 609 ms.
It will even become 1500ms if the idle tasks belongs to an idle cgroup.
This means that the scheduler will look for picking another waiting task
after 609ms running time (1500ms respectively). The idle tasks change
significantly the way the 2 normal tasks interleave their running time
slot whereas they should have a small impact.
Such long sched_slice can delay significantly the release of resources
as the tasks can wait hundreds of ms before the next running slot just
because of idle tasks queued on the rq.
Cap the ideal_runtime to sysctl_sched_latency to make sure that tasks will
regularly make progress and will not be significantly impacted by
idle/background tasks queued on the rq.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20230113133613.257342-1-vincent.guittot@linaro.org
Current arch_cpu_idle() is called with IRQs disabled, but will return
with IRQs enabled.
However, the very first thing the generic code does after calling
arch_cpu_idle() is raw_local_irq_disable(). This means that
architectures that can idle with IRQs disabled end up doing a
pointless 'enable-disable' dance.
Therefore, push this IRQ disabling into the idle function, meaning
that those architectures can avoid the pointless IRQ state flipping.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Acked-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Guo Ren <guoren@kernel.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195540.618076436@infradead.org
The whole disable-RCU, enable-IRQS dance is very intricate since
changing IRQ state is traced, which depends on RCU.
Add two helpers for the cpuidle case that mirror the entry code:
ct_cpuidle_enter()
ct_cpuidle_exit()
And fix all the cases where the enter/exit dance was buggy.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195540.130014793@infradead.org
Traversing the Perf Domains requires rcu_read_lock() to be held and is
conditional on sched_energy_enabled(). Ensure right protections applied.
Also skip capacity inversion detection for our own pd; which was an
error.
Fixes: 44c7b80bff ("sched/fair: Detect capacity inversion")
Reported-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Qais Yousef (Google) <qyousef@layalina.io>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20230112122708.330667-3-qyousef@layalina.io
Commit 851a723e45 ("sched: Always clear user_cpus_ptr in
do_set_cpus_allowed()") may call kfree() if user_cpus_ptr was previously
set. Unfortunately, some of the callers of do_set_cpus_allowed()
may have pi_lock held when calling it. So the following splats may be
printed especially when running with a PREEMPT_RT kernel:
WARNING: possible circular locking dependency detected
BUG: sleeping function called from invalid context
To avoid these problems, kfree_rcu() is used instead. An internal
cpumask_rcuhead union is created for the sole purpose of facilitating
the use of kfree_rcu() to free the cpumask.
Since user_cpus_ptr is not being used in non-SMP configs, the newly
introduced alloc_user_cpus_ptr() helper will return NULL in this case
and sched_setaffinity() is modified to handle this special case.
Fixes: 851a723e45 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()")
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221231041120.440785-3-longman@redhat.com
Since commit 07ec77a1d4 ("sched: Allow task CPU affinity to be
restricted on asymmetric systems"), the setting and clearing of
user_cpus_ptr are done under pi_lock for arm64 architecture. However,
dup_user_cpus_ptr() accesses user_cpus_ptr without any lock
protection. Since sched_setaffinity() can be invoked from another
process, the process being modified may be undergoing fork() at
the same time. When racing with the clearing of user_cpus_ptr in
__set_cpus_allowed_ptr_locked(), it can lead to user-after-free and
possibly double-free in arm64 kernel.
Commit 8f9ea86fdf ("sched: Always preserve the user requested
cpumask") fixes this problem as user_cpus_ptr, once set, will never
be cleared in a task's lifetime. However, this bug was re-introduced
in commit 851a723e45 ("sched: Always clear user_cpus_ptr in
do_set_cpus_allowed()") which allows the clearing of user_cpus_ptr in
do_set_cpus_allowed(). This time, it will affect all arches.
Fix this bug by always clearing the user_cpus_ptr of the newly
cloned/forked task before the copying process starts and check the
user_cpus_ptr state of the source task under pi_lock.
Note to stable, this patch won't be applicable to stable releases.
Just copy the new dup_user_cpus_ptr() function over.
Fixes: 07ec77a1d4 ("sched: Allow task CPU affinity to be restricted on asymmetric systems")
Fixes: 851a723e45 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()")
Reported-by: David Wang 王标 <wangbiao3@xiaomi.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20221231041120.440785-2-longman@redhat.com
In order for the scheduler to be frequency invariant we measure the
ratio between the maximum CPU frequency and the actual CPU frequency.
During long tickless periods of time the calculations that keep track
of that might overflow, in the function scale_freq_tick():
if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt))
goto error;
eventually forcing the kernel to disable the feature for all CPUs,
and show the warning message:
"Scheduler frequency invariance went wobbly, disabling!".
Let's avoid that by limiting the frequency invariant calculations
to CPUs with regular tick.
Fixes: e2b0d619b4 ("x86, sched: check for counters overflow in frequency invariant accounting")
Suggested-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: Yair Podemsky <ypodemsk@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Acked-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Link: https://lore.kernel.org/r/20221130125121.34407-1-ypodemsk@redhat.com
Provide a method to query previously issued registrations.
Signed-off-by: Michal Clapinski <mclapinski@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20221207164338.1535591-2-mclapinski@google.com
The max CPU capacity is the same for all CPUs sharing frequency domain.
There is a way to avoid heavy operations in a loop for each CPU by
leveraging this knowledge. Thus, simplify the looping code in the
sugov_next_freq_shared() and drop heavy multiplications. Instead, use
simple max() to get the highest utilization from these CPUs.
This is useful for platforms with many (4 or 6) little CPUs. We avoid
heavy 2*PD_CPU_NUM multiplications in that loop, which is called billions
of times, since it's not limited by the schedutil time delta filter in
sugov_should_update_freq(). When there was no need to change frequency
the code bailed out, not updating the sg_policy::last_freq_update_time.
Then every visit after delta_ns time longer than the
sg_policy::freq_update_delay_ns goes through and triggers the next
frequency calculation code. Although, if the next frequency, as outcome
of that, would be the same as current frequency, we won't update the
sg_policy::last_freq_update_time and the story will be repeated (in
a very short period, sometimes a few microseconds).
The max CPU capacity must be fetched every time we are called, due to
difficulties during the policy setup, where we are not able to get the
normalized CPU capacity at the right time.
The fetched CPU capacity value is than used in sugov_iowait_apply() to
calculate the right boost. This required a few changes in the local
functions and arguments. The capacity value should hopefully be fetched
once when needed and then passed over CPU registers to those functions.
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20221208160256.859-2-lukasz.luba@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
ttwu_do_activate() is used for a complete wakeup, in which we will
activate_task() and use ttwu_do_wakeup() to mark the task runnable
and perform wakeup-preemption, also call class->task_woken() callback
and update the rq->idle_stamp.
Since ttwu_runnable() is not a complete wakeup, don't need all those
done in ttwu_do_wakeup(), so we can move those to ttwu_do_activate()
to simplify ttwu_do_wakeup(), making it only mark the task runnable
to be reused in ttwu_runnable() and try_to_wake_up().
This patch should not have any functional changes.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20221223103257.4962-2-zhouchengming@bytedance.com
ttwu_runnable() is used as a fast wakeup path when the wakee task
is running on CPU or runnable on RQ, in both cases we can just
set its state to TASK_RUNNING to prevent a sleep.
If the wakee task is on_cpu running, we don't need to update_rq_clock()
or check_preempt_curr().
But if the wakee task is on_rq && !on_cpu (e.g. an IRQ hit before
the task got to schedule() and the task been preempted), we should
check_preempt_curr() to see if it can preempt the current running.
This also removes the class->task_woken() callback from ttwu_runnable(),
which wasn't required per the RT/DL implementations: any required push
operation would have been queued during class->set_next_task() when p
got preempted.
ttwu_runnable() also loses the update to rq->idle_stamp, as by definition
the rq cannot be idle in this scenario.
Suggested-by: Valentin Schneider <vschneid@redhat.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20221223103257.4962-1-zhouchengming@bytedance.com
Add a function nr_context_switches_cpu() that returns number of context
switches since boot on the specified CPU. This information will be used
to diagnose RCU CPU stalls.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
sched_mm_cid_after_execve() does not expect NULL t->mm, but it may happen
if a usermodehelper kthread fails when attempting to execute a binary.
sched_mm_cid_fork() can be issued from a usermodehelper kthread, which
has t->flags PF_KTHREAD set.
Fixes: af7f588d8f ("sched: Introduce per-memory-map concurrency ID")
Reported-by: kernel test robot <yujie.liu@intel.com>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/oe-lkp/202212301353.5c959d72-yujie.liu@intel.com
The archs that use cputime_to_nsecs() internally provide their own
definition and don't need the fallback. cputime_to_usecs() unused except
in this fallback, and is not defined anywhere.
This removes the final remnant of the cputime_t code from the kernel.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/r/20221220070705.2958959-1-npiggin@gmail.com
When select_idle_capacity() starts scanning for an idle CPU, it starts
with target CPU that has already been checked in select_idle_sibling().
So we start checking from the next CPU and try the target CPU at the end.
Similarly for task_numa_assign(), we have just checked numa_migrate_on
of dst_cpu, so start from the next CPU. This also works for
steal_cookie_task(), the first scan must fail and start directly
from the next one.
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Link: https://lore.kernel.org/r/20221216062406.7812-3-jiahao.os@bytedance.com
In update_numa_stats() we try to find an idle cpu on the NUMA node,
preferably an idle core. we can stop looking for the next idle core
or idle cpu after finding an idle core. But we can't stop the
whole loop of scanning the CPU, because we need to calculate
approximate NUMA stats at a point in time. For example,
the src and dst nr_running is needed by task_numa_find_cpu().
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Link: https://lore.kernel.org/r/20221216062406.7812-2-jiahao.os@bytedance.com
With a modified container_of() that preserves constness, the compiler
finds some pointers which should have been marked as const. task_of()
also needs to become const-preserving for the !FAIR_GROUP_SCHED case so
that cfs_rq_of() can take a const argument. No change to generated code.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221212144946.2657785-1-willy@infradead.org
This feature allows the scheduler to expose a per-memory map concurrency
ID to user-space. This concurrency ID is within the possible cpus range,
and is temporarily (and uniquely) assigned while threads are actively
running within a memory map. If a memory map has fewer threads than
cores, or is limited to run on few cores concurrently through sched
affinity or cgroup cpusets, the concurrency IDs will be values close
to 0, thus allowing efficient use of user-space memory for per-cpu
data structures.
This feature is meant to be exposed by a new rseq thread area field.
The primary purpose of this feature is to do the heavy-lifting needed
by memory allocators to allow them to use per-cpu data structures
efficiently in the following situations:
- Single-threaded applications,
- Multi-threaded applications on large systems (many cores) with limited
cpu affinity mask,
- Multi-threaded applications on large systems (many cores) with
restricted cgroup cpuset per container.
One of the key concern from scheduler maintainers is the overhead
associated with additional spin locks or atomic operations in the
scheduler fast-path. This is why the following optimization is
implemented.
On context switch between threads belonging to the same memory map,
transfer the mm_cid from prev to next without any atomic ops. This
takes care of use-cases involving frequent context switch between
threads belonging to the same memory map.
Additional optimizations can be done if the spin locks added when
context switching between threads belonging to different memory maps end
up being a performance bottleneck. Those are left out of this patch
though. A performance impact would have to be clearly demonstrated to
justify the added complexity.
The credit goes to Paul Turner (Google) for the original virtual cpu id
idea. This feature is implemented based on the discussions with Paul
Turner and Peter Oskolkov (Google), but I took the liberty to implement
scheduler fast-path optimizations and my own NUMA-awareness scheme. The
rumor has it that Google have been running a rseq vcpu_id extension
internally in production for a year. The tcmalloc source code indeed has
comments hinting at a vcpu_id prototype extension to the rseq system
call [1].
The following benchmarks do not show any significant overhead added to
the scheduler context switch by this feature:
* perf bench sched messaging (process)
Baseline: 86.5±0.3 ms
With mm_cid: 86.7±2.6 ms
* perf bench sched messaging (threaded)
Baseline: 84.3±3.0 ms
With mm_cid: 84.7±2.6 ms
* hackbench (process)
Baseline: 82.9±2.7 ms
With mm_cid: 82.9±2.9 ms
* hackbench (threaded)
Baseline: 85.2±2.6 ms
With mm_cid: 84.4±2.9 ms
[1] https://github.com/google/tcmalloc/blob/master/tcmalloc/internal/linux_syscall_support.h#L26
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221122203932.231377-8-mathieu.desnoyers@efficios.com
CFS bandwidth currently distributes new runtime and unthrottles cfs_rq's
inline in an hrtimer callback. Runtime distribution is a per-cpu
operation, and unthrottling is a per-cgroup operation, since a tg walk
is required. On machines with a large number of cpus and large cgroup
hierarchies, this cpus*cgroups work can be too much to do in a single
hrtimer callback: since IRQ are disabled, hard lockups may easily occur.
Specifically, we've found this scalability issue on configurations with
256 cpus, O(1000) cgroups in the hierarchy being throttled, and high
memory bandwidth usage.
To fix this, we can instead unthrottle cfs_rq's asynchronously via a
CSD. Each cpu is responsible for unthrottling itself, thus sharding the
total work more fairly across the system, and avoiding hard lockups.
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221117005418.3499691-1-joshdon@google.com
init_defrootdomain is only used in initialization
Signed-off-by: Bing Huang <huangbing@kylinos.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lkml.kernel.org/r/20221118034208.267330-1-huangbing775@126.com
- Convert flexible array members, fix -Wstringop-overflow warnings,
and fix KCFI function type mismatches that went ignored by
maintainers (Gustavo A. R. Silva, Nathan Chancellor, Kees Cook).
- Remove the remaining side-effect users of ksize() by converting
dma-buf, btrfs, and coredump to using kmalloc_size_roundup(),
add more __alloc_size attributes, and introduce full testing
of all allocator functions. Finally remove the ksize() side-effect
so that each allocation-aware checker can finally behave without
exceptions.
- Introduce oops_limit (default 10,000) and warn_limit (default off)
to provide greater granularity of control for panic_on_oops and
panic_on_warn (Jann Horn, Kees Cook).
- Introduce overflows_type() and castable_to_type() helpers for
cleaner overflow checking.
- Improve code generation for strscpy() and update str*() kern-doc.
- Convert strscpy and sigphash tests to KUnit, and expand memcpy
tests.
- Always use a non-NULL argument for prepare_kernel_cred().
- Disable structleak plugin in FORTIFY KUnit test (Anders Roxell).
- Adjust orphan linker section checking to respect CONFIG_WERROR
(Xin Li).
- Make sure siginfo is cleared for forced SIGKILL (haifeng.xu).
- Fix um vs FORTIFY warnings for always-NULL arguments.
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Merge tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull kernel hardening updates from Kees Cook:
- Convert flexible array members, fix -Wstringop-overflow warnings, and
fix KCFI function type mismatches that went ignored by maintainers
(Gustavo A. R. Silva, Nathan Chancellor, Kees Cook)
- Remove the remaining side-effect users of ksize() by converting
dma-buf, btrfs, and coredump to using kmalloc_size_roundup(), add
more __alloc_size attributes, and introduce full testing of all
allocator functions. Finally remove the ksize() side-effect so that
each allocation-aware checker can finally behave without exceptions
- Introduce oops_limit (default 10,000) and warn_limit (default off) to
provide greater granularity of control for panic_on_oops and
panic_on_warn (Jann Horn, Kees Cook)
- Introduce overflows_type() and castable_to_type() helpers for cleaner
overflow checking
- Improve code generation for strscpy() and update str*() kern-doc
- Convert strscpy and sigphash tests to KUnit, and expand memcpy tests
- Always use a non-NULL argument for prepare_kernel_cred()
- Disable structleak plugin in FORTIFY KUnit test (Anders Roxell)
- Adjust orphan linker section checking to respect CONFIG_WERROR (Xin
Li)
- Make sure siginfo is cleared for forced SIGKILL (haifeng.xu)
- Fix um vs FORTIFY warnings for always-NULL arguments
* tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (31 commits)
ksmbd: replace one-element arrays with flexible-array members
hpet: Replace one-element array with flexible-array member
um: virt-pci: Avoid GCC non-NULL warning
signal: Initialize the info in ksignal
lib: fortify_kunit: build without structleak plugin
panic: Expose "warn_count" to sysfs
panic: Introduce warn_limit
panic: Consolidate open-coded panic_on_warn checks
exit: Allow oops_limit to be disabled
exit: Expose "oops_count" to sysfs
exit: Put an upper limit on how often we can oops
panic: Separate sysctl logic from CONFIG_SMP
mm/pgtable: Fix multiple -Wstringop-overflow warnings
mm: Make ksize() a reporting-only function
kunit/fortify: Validate __alloc_size attribute results
drm/sti: Fix return type of sti_{dvo,hda,hdmi}_connector_mode_valid()
drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
driver core: Add __alloc_size hint to devm allocators
overflow: Introduce overflows_type() and castable_to_type()
coredump: Proactively round up to kmalloc bucket size
...
Only step forward on the sysctl cleanups for this cycle. This
has been on linux-next since September and this time it goes
with a "Yeah, think so, it just moves stuff around a bit" from
Peter Zijlstra.
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Merge tag 'sysctl-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux
Pull sysctl updates from Luis Chamberlain:
"Only a small step forward on the sysctl cleanups for this cycle"
* tag 'sysctl-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
sched: Move numa_balancing sysctls to its own file
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Merge tag 'for-6.2/block-2022-12-08' of git://git.kernel.dk/linux
Pull block updates from Jens Axboe:
- NVMe pull requests via Christoph:
- Support some passthrough commands without CAP_SYS_ADMIN (Kanchan
Joshi)
- Refactor PCIe probing and reset (Christoph Hellwig)
- Various fabrics authentication fixes and improvements (Sagi
Grimberg)
- Avoid fallback to sequential scan due to transient issues (Uday
Shankar)
- Implement support for the DEAC bit in Write Zeroes (Christoph
Hellwig)
- Allow overriding the IEEE OUI and firmware revision in configfs
for nvmet (Aleksandr Miloserdov)
- Force reconnect when number of queue changes in nvmet (Daniel
Wagner)
- Minor fixes and improvements (Uros Bizjak, Joel Granados, Sagi
Grimberg, Christoph Hellwig, Christophe JAILLET)
- Fix and cleanup nvme-fc req allocation (Chaitanya Kulkarni)
- Use the common tagset helpers in nvme-pci driver (Christoph
Hellwig)
- Cleanup the nvme-pci removal path (Christoph Hellwig)
- Use kstrtobool() instead of strtobool (Christophe JAILLET)
- Allow unprivileged passthrough of Identify Controller (Joel
Granados)
- Support io stats on the mpath device (Sagi Grimberg)
- Minor nvmet cleanup (Sagi Grimberg)
- MD pull requests via Song:
- Code cleanups (Christoph)
- Various fixes
- Floppy pull request from Denis:
- Fix a memory leak in the init error path (Yuan)
- Series fixing some batch wakeup issues with sbitmap (Gabriel)
- Removal of the pktcdvd driver that was deprecated more than 5 years
ago, and subsequent removal of the devnode callback in struct
block_device_operations as no users are now left (Greg)
- Fix for partition read on an exclusively opened bdev (Jan)
- Series of elevator API cleanups (Jinlong, Christoph)
- Series of fixes and cleanups for blk-iocost (Kemeng)
- Series of fixes and cleanups for blk-throttle (Kemeng)
- Series adding concurrent support for sync queues in BFQ (Yu)
- Series bringing drbd a bit closer to the out-of-tree maintained
version (Christian, Joel, Lars, Philipp)
- Misc drbd fixes (Wang)
- blk-wbt fixes and tweaks for enable/disable (Yu)
- Fixes for mq-deadline for zoned devices (Damien)
- Add support for read-only and offline zones for null_blk
(Shin'ichiro)
- Series fixing the delayed holder tracking, as used by DM (Yu,
Christoph)
- Series enabling bio alloc caching for IRQ based IO (Pavel)
- Series enabling userspace peer-to-peer DMA (Logan)
- BFQ waker fixes (Khazhismel)
- Series fixing elevator refcount issues (Christoph, Jinlong)
- Series cleaning up references around queue destruction (Christoph)
- Series doing quiesce by tagset, enabling cleanups in drivers
(Christoph, Chao)
- Series untangling the queue kobject and queue references (Christoph)
- Misc fixes and cleanups (Bart, David, Dawei, Jinlong, Kemeng, Ye,
Yang, Waiman, Shin'ichiro, Randy, Pankaj, Christoph)
* tag 'for-6.2/block-2022-12-08' of git://git.kernel.dk/linux: (247 commits)
blktrace: Fix output non-blktrace event when blk_classic option enabled
block: sed-opal: Don't include <linux/kernel.h>
sed-opal: allow using IOC_OPAL_SAVE for locking too
blk-cgroup: Fix typo in comment
block: remove bio_set_op_attrs
nvmet: don't open-code NVME_NS_ATTR_RO enumeration
nvme-pci: use the tagset alloc/free helpers
nvme: add the Apple shared tag workaround to nvme_alloc_io_tag_set
nvme: only set reserved_tags in nvme_alloc_io_tag_set for fabrics controllers
nvme: consolidate setting the tagset flags
nvme: pass nr_maps explicitly to nvme_alloc_io_tag_set
block: bio_copy_data_iter
nvme-pci: split out a nvme_pci_ctrl_is_dead helper
nvme-pci: return early on ctrl state mismatch in nvme_reset_work
nvme-pci: rename nvme_disable_io_queues
nvme-pci: cleanup nvme_suspend_queue
nvme-pci: remove nvme_pci_disable
nvme-pci: remove nvme_disable_admin_queue
nvme: merge nvme_shutdown_ctrl into nvme_disable_ctrl
nvme: use nvme_wait_ready in nvme_shutdown_ctrl
...
- A ptrace API cleanup series from Sergey Shtylyov
- Fixes and cleanups for kexec from ye xingchen
- nilfs2 updates from Ryusuke Konishi
- squashfs feature work from Xiaoming Ni: permit configuration of the
filesystem's compression concurrency from the mount command line.
- A series from Akinobu Mita which addresses bound checking errors when
writing to debugfs files.
- A series from Yang Yingliang to address rapido memory leaks
- A series from Zheng Yejian to address possible overflow errors in
encode_comp_t().
- And a whole shower of singleton patches all over the place.
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Merge tag 'mm-nonmm-stable-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
- A ptrace API cleanup series from Sergey Shtylyov
- Fixes and cleanups for kexec from ye xingchen
- nilfs2 updates from Ryusuke Konishi
- squashfs feature work from Xiaoming Ni: permit configuration of the
filesystem's compression concurrency from the mount command line
- A series from Akinobu Mita which addresses bound checking errors when
writing to debugfs files
- A series from Yang Yingliang to address rapidio memory leaks
- A series from Zheng Yejian to address possible overflow errors in
encode_comp_t()
- And a whole shower of singleton patches all over the place
* tag 'mm-nonmm-stable-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (79 commits)
ipc: fix memory leak in init_mqueue_fs()
hfsplus: fix bug causing custom uid and gid being unable to be assigned with mount
rapidio: devices: fix missing put_device in mport_cdev_open
kcov: fix spelling typos in comments
hfs: Fix OOB Write in hfs_asc2mac
hfs: fix OOB Read in __hfs_brec_find
relay: fix type mismatch when allocating memory in relay_create_buf()
ocfs2: always read both high and low parts of dinode link count
io-mapping: move some code within the include guarded section
kernel: kcsan: kcsan_test: build without structleak plugin
mailmap: update email for Iskren Chernev
eventfd: change int to __u64 in eventfd_signal() ifndef CONFIG_EVENTFD
rapidio: fix possible UAF when kfifo_alloc() fails
relay: use strscpy() is more robust and safer
cpumask: limit visibility of FORCE_NR_CPUS
acct: fix potential integer overflow in encode_comp_t()
acct: fix accuracy loss for input value of encode_comp_t()
linux/init.h: include <linux/build_bug.h> and <linux/stringify.h>
rapidio: rio: fix possible name leak in rio_register_mport()
rapidio: fix possible name leaks when rio_add_device() fails
...
- Implement persistent user-requested affinity: introduce affinity_context::user_mask
and unconditionally preserve the user-requested CPU affinity masks, for long-lived
tasks to better interact with cpusets & CPU hotplug events over longer timespans,
without destroying the original affinity intent if the underlying topology changes.
- Uclamp updates: fix relationship between uclamp and fits_capacity()
- PSI fixes
- Misc fixes & updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Implement persistent user-requested affinity: introduce
affinity_context::user_mask and unconditionally preserve the
user-requested CPU affinity masks, for long-lived tasks to better
interact with cpusets & CPU hotplug events over longer timespans,
without destroying the original affinity intent if the underlying
topology changes.
- Uclamp updates: fix relationship between uclamp and fits_capacity()
- PSI fixes
- Misc fixes & updates
* tag 'sched-core-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Clear ttwu_pending after enqueue_task()
sched/psi: Use task->psi_flags to clear in CPU migration
sched/psi: Stop relying on timer_pending() for poll_work rescheduling
sched/psi: Fix avgs_work re-arm in psi_avgs_work()
sched/psi: Fix possible missing or delayed pending event
sched: Always clear user_cpus_ptr in do_set_cpus_allowed()
sched: Enforce user requested affinity
sched: Always preserve the user requested cpumask
sched: Introduce affinity_context
sched: Add __releases annotations to affine_move_task()
sched/fair: Check if prev_cpu has highest spare cap in feec()
sched/fair: Consider capacity inversion in util_fits_cpu()
sched/fair: Detect capacity inversion
sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition
sched/uclamp: Make cpu_overutilized() use util_fits_cpu()
sched/uclamp: Make asym_fits_capacity() use util_fits_cpu()
sched/uclamp: Make select_idle_capacity() use util_fits_cpu()
sched/uclamp: Fix fits_capacity() check in feec()
sched/uclamp: Make task_fits_capacity() use util_fits_cpu()
sched/uclamp: Fix relationship between uclamp and migration margin
Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll
their own warnings, and each check "panic_on_warn". Consolidate this
into a single function so that future instrumentation can be added in
a single location.
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Gow <davidgow@google.com>
Cc: tangmeng <tangmeng@uniontech.com>
Cc: Jann Horn <jannh@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: kasan-dev@googlegroups.com
Cc: linux-mm@kvack.org
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20221117234328.594699-4-keescook@chromium.org
This reverts commit 6d5afdc97e.
On a Pixel 6 device, it is observed that this commit increases
latency by approximately 50ms, or 20%, in migrating a task
that requires full CPU utilization from a LITTLE CPU to Fmax
on a big CPU. Reverting this change restores the latency back
to its original baseline value.
Fixes: 6d5afdc97e ("cpufreq: schedutil: Move max CPU capacity to sugov_policy")
Signed-off-by: Sam Wu <wusamuel@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The sysctl_numa_balancing_promote_rate_limit and sysctl_numa_balancing
are part of sched, move them to its own file.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in
task_numa_work. x86 CMPXCHG instruction returns success in ZF flag, so
this change saves a compare after cmpxchg (and related move instruction in
front of cmpxchg).
No functional change intended.
Link: https://lkml.kernel.org/r/20220822173956.82525-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Sbitmap code will need to know how many waiters were actually woken for
its batched wakeups implementation. Return the number of woken
exclusive waiters from __wake_up() to facilitate that.
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20221115224553.23594-3-krisman@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We found a long tail latency in schbench whem m*t is close to nr_cpus.
(e.g., "schbench -m 2 -t 16" on a machine with 32 cpus.)
This is because when the wakee cpu is idle, rq->ttwu_pending is cleared
too early, and idle_cpu() will return true until the wakee task enqueued.
This will mislead the waker when selecting idle cpu, and wake multiple
worker threads on the same wakee cpu. This situation is enlarged by
commit f3dd3f6745 ("sched: Remove the limitation of WF_ON_CPU on
wakelist if wakee cpu is idle") because it tends to use wakelist.
Here is the result of "schbench -m 2 -t 16" on a VM with 32vcpu
(Intel(R) Xeon(R) Platinum 8369B).
Latency percentiles (usec):
base base+revert_f3dd3f674555 base+this_patch
50.0000th: 9 13 9
75.0000th: 12 19 12
90.0000th: 15 22 15
95.0000th: 18 24 17
*99.0000th: 27 31 24
99.5000th: 3364 33 27
99.9000th: 12560 36 30
We also tested on unixbench and hackbench, and saw no performance
change.
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lkml.kernel.org/r/20221104023601.12844-1-dtcccc@linux.alibaba.com
There is a very narrow race between schedule() and task_call_func().
CPU0 CPU1
__schedule()
rq_lock();
prev_state = READ_ONCE(prev->__state);
if (... && prev_state) {
deactivate_tasl(rq, prev, ...)
prev->on_rq = 0;
task_call_func()
raw_spin_lock_irqsave(p->pi_lock);
state = READ_ONCE(p->__state);
smp_rmb();
if (... || p->on_rq) // false!!!
rq = __task_rq_lock()
ret = func();
next = pick_next_task();
rq = context_switch(prev, next)
prepare_lock_switch()
spin_release(&__rq_lockp(rq)->dep_map...)
So while the task is on it's way out, it still holds rq->lock for a
little while, and right then task_call_func() comes in and figures it
doesn't need rq->lock anymore (because the task is already dequeued --
but still running there) and then the __set_task_frozen() thing observes
it's holding rq->lock and yells murder.
Avoid this by waiting for p->on_cpu to get cleared, which guarantees
the task is fully finished on the old CPU.
( While arguably the fixes tag is 'wrong' -- none of the previous
task_call_func() users appears to care for this case. )
Fixes: f5d39b0208 ("freezer,sched: Rewrite core freezer logic")
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lkml.kernel.org/r/Y1kdRNNfUeAU+FNl@hirez.programming.kicks-ass.net
