linux-yocto/Documentation/scheduler
Vincent Guittot 7fc781ca93 sched/topology: Consolidate and clean up access to a CPU's max compute capacity
[ Upstream commit 7bc263840b ]

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
Stable-dep-of: 79443a7e9d ("cpufreq/sched: Explicitly synchronize limits_changed flag handling")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-05-02 07:50:41 +02:00
..
completion.rst
index.rst
sched-arch.rst
sched-bwc.rst
sched-capacity.rst
sched-deadline.rst
sched-debug.rst
sched-design-CFS.rst
sched-domains.rst
sched-energy.rst
sched-nice-design.rst
sched-pelt.c
sched-rt-group.rst
sched-stats.rst
sched-util-clamp.rst
schedutil.rst
text_files.rst