MIRRORS/linux-yocto
1
0
Fork 0
mirror of git://git.yoctoproject.org/linux-yocto.git synced 2025-10-23 07:23:12 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

cpuidle: teo: Simplify counting events used for tick management

Browse Source 
Replace the tick_hits metric with a new tick_intercepts one that can be
used directly when deciding whether or not to stop the scheduler tick
and update the governor functional description accordingly.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
Tested-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/1987985.PYKUYFuaPT@rjwysocki.net
This commit is contained in:
Rafael J. Wysocki 2025-01-13 19:45:50 +01:00
parent e24f8a55de
commit d619b5cc67
1 changed files with 14 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
drivers/cpuidle/governors/teo.c
View File

@ -41,11 +41,7 @@
* idle state 2, the third bin spans from the target residency of idle state 2
* up to, but not including, the target residency of idle state 3 and so on.
* The last bin spans from the target residency of the deepest idle state
* supplied by the driver to the scheduler tick period length or to infinity if
* the tick period length is less than the target residency of that state. In
* the latter case, the governor also counts events with the measured idle
* duration between the tick period length and the target residency of the
* deepest idle state.
* supplied by the driver to infinity.
*
* Two metrics called "hits" and "intercepts" are associated with each bin.
* They are updated every time before selecting an idle state for the given CPU
@ -60,6 +56,10 @@
* into by the sleep length (these events are also referred to as "intercepts"
* below).
*
* The governor also counts "intercepts" with the measured idle duration below
* the tick period length and uses this information when deciding whether or not
* to stop the scheduler tick.
*
* In order to select an idle state for a CPU, the governor takes the following
* steps (modulo the possible latency constraint that must be taken into account
* too):
@ -128,14 +128,14 @@ struct teo_bin {
* @sleep_length_ns: Time till the closest timer event (at the selection time).
* @state_bins: Idle state data bins for this CPU.
* @total: Grand total of the "intercepts" and "hits" metrics for all bins.
* @tick_hits: Number of "hits" after TICK_NSEC.
* @tick_intercepts: "Intercepts" before TICK_NSEC.
*/
struct teo_cpu {
s64 time_span_ns;
s64 sleep_length_ns;
struct teo_bin state_bins[CPUIDLE_STATE_MAX];
unsigned int total;
unsigned int tick_hits;
unsigned int tick_intercepts;
};
static DEFINE_PER_CPU(struct teo_cpu, teo_cpus);
@ -207,38 +207,21 @@ static void teo_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
}
}
/*
* If the deepest state's target residency is below the tick length,
* make a record of it to help teo_select() decide whether or not
* to stop the tick. This effectively adds an extra hits-only bin
* beyond the last state-related one.
*/
if (target_residency_ns < TICK_NSEC) {
cpu_data->tick_hits -= cpu_data->tick_hits >> DECAY_SHIFT;
cpu_data->total += cpu_data->tick_hits;
if (TICK_NSEC <= cpu_data->sleep_length_ns) {
idx_timer = drv->state_count;
if (TICK_NSEC <= measured_ns) {
cpu_data->tick_hits += PULSE;
goto end;
}
}
}
cpu_data->tick_intercepts -= cpu_data->tick_intercepts >> DECAY_SHIFT;
/*
* If the measured idle duration falls into the same bin as the sleep
* length, this is a "hit", so update the "hits" metric for that bin.
* Otherwise, update the "intercepts" metric for the bin fallen into by
* the measured idle duration.
*/
if (idx_timer == idx_duration)
if (idx_timer == idx_duration) {
cpu_data->state_bins[idx_timer].hits += PULSE;
else
} else {
cpu_data->state_bins[idx_duration].intercepts += PULSE;
if (TICK_NSEC <= measured_ns)
cpu_data->tick_intercepts += PULSE;
}
end:
cpu_data->total += PULSE;
}
@ -286,7 +269,6 @@ static int teo_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
struct teo_cpu *cpu_data = per_cpu_ptr(&teo_cpus, dev->cpu);
s64 latency_req = cpuidle_governor_latency_req(dev->cpu);
ktime_t delta_tick = TICK_NSEC / 2;
unsigned int tick_intercept_sum = 0;
unsigned int idx_intercept_sum = 0;
unsigned int intercept_sum = 0;
unsigned int idx_hit_sum = 0;
@ -365,9 +347,6 @@ static int teo_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
goto end;
}
tick_intercept_sum = intercept_sum +
cpu_data->state_bins[drv->state_count-1].intercepts;
/*
* If the sum of the intercepts metric for all of the idle states
* shallower than the current candidate one (idx) is greater than the
@ -477,7 +456,7 @@ static int teo_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
* total wakeup events, do not stop the tick.
*/
if (drv->states[idx].target_residency_ns < TICK_NSEC &&
tick_intercept_sum > cpu_data->total / 2 + cpu_data->total / 8)
cpu_data->tick_intercepts > cpu_data->total / 2 + cpu_data->total / 8)
duration_ns = TICK_NSEC / 2;
end: