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sched/fair: Make task_fits_capacity() consider uclamp restrictions 

task_fits_capacity() drives CPU selection at wakeup time, and is also used
to detect misfit tasks. Right now it does so by comparing task_util_est()
with a CPU's capacity, but doesn't take into account uclamp restrictions.

There's a few interesting uses that can come out of doing this. For
instance, a low uclamp.max value could prevent certain tasks from being
flagged as misfit tasks, so they could merrily remain on low-capacity CPUs.
Similarly, a high uclamp.min value would steer tasks towards high capacity
CPUs at wakeup (and, should that fail, later steered via misfit balancing),
so such "boosted" tasks would favor CPUs of higher capacity.

Introduce uclamp_task_util() and make task_fits_capacity() use it.

Tested-By: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191211113851.24241-5-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
alistair/sensors
Valentin Schneider 2019-12-11 11:38:50 +00:00 committed by Ingo Molnar
parent d2b58a286e
commit a7008c07a5
1 changed files with 15 additions and 1 deletions
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16
kernel/sched/fair.c
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@ -3711,6 +3711,20 @@ static inline unsigned long task_util_est(struct task_struct *p)
return max(task_util(p), _task_util_est(p));
}
#ifdef CONFIG_UCLAMP_TASK
static inline unsigned long uclamp_task_util(struct task_struct *p)
{
return clamp(task_util_est(p),
uclamp_eff_value(p, UCLAMP_MIN),
uclamp_eff_value(p, UCLAMP_MAX));
}
#else
static inline unsigned long uclamp_task_util(struct task_struct *p)
{
return task_util_est(p);
}
#endif
static inline void util_est_enqueue(struct cfs_rq *cfs_rq,
struct task_struct *p)
{
@ -3822,7 +3836,7 @@ done:
static inline int task_fits_capacity(struct task_struct *p, long capacity)
{
return fits_capacity(task_util_est(p), capacity);
return fits_capacity(uclamp_task_util(p), capacity);
}
static inline void update_misfit_status(struct task_struct *p, struct rq *rq)