Commit 2d02fa8c authored by Vincent Guittot's avatar Vincent Guittot Committed by Peter Zijlstra
Browse files

sched/pelt: Relax the sync of load_sum with load_avg 



Similarly to util_avg and util_sum, don't sync load_sum with the low
bound of load_avg but only ensure that load_sum stays in the correct range.

Signed-off-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: default avatarSachin Sant <sachinp@linux.ibm.com>
Link: https://lkml.kernel.org/r/20220111134659.24961-5-vincent.guittot@linaro.org
parent 95246d1e

kernel/sched/fair.c

+22 −14
Original line number Diff line number Diff line
@@ -3028,9 +3028,11 @@ enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) 
static inline void

dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)

{

	u32 divider = get_pelt_divider(&se->avg);

	sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);

	cfs_rq->avg.load_sum = cfs_rq->avg.load_avg * divider;

	sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum);

	/* See update_cfs_rq_load_avg() */

	cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,

					  cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);

}

#else

static inline void
@@ -3513,9 +3515,10 @@ update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cf 
static inline void

update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)

{

	long delta, running_sum, runnable_sum = gcfs_rq->prop_runnable_sum;

	long delta_avg, running_sum, runnable_sum = gcfs_rq->prop_runnable_sum;

	unsigned long load_avg;

	u64 load_sum = 0;

	s64 delta_sum;

	u32 divider;



	if (!runnable_sum)
@@ -3542,7 +3545,7 @@ update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq 
		 * assuming all tasks are equally runnable.

		 */

		if (scale_load_down(gcfs_rq->load.weight)) {

			load_sum = div_s64(gcfs_rq->avg.load_sum,

			load_sum = div_u64(gcfs_rq->avg.load_sum,

				scale_load_down(gcfs_rq->load.weight));

		}
@@ -3559,19 +3562,22 @@ update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq 
	running_sum = se->avg.util_sum >> SCHED_CAPACITY_SHIFT;

	runnable_sum = max(runnable_sum, running_sum);



	load_sum = (s64)se_weight(se) * runnable_sum;

	load_avg = div_s64(load_sum, divider);

	load_sum = se_weight(se) * runnable_sum;

	load_avg = div_u64(load_sum, divider);



	se->avg.load_sum = runnable_sum;



	delta = load_avg - se->avg.load_avg;

	if (!delta)

	delta_avg = load_avg - se->avg.load_avg;

	if (!delta_avg)

		return;



	se->avg.load_avg = load_avg;

	delta_sum = load_sum - (s64)se_weight(se) * se->avg.load_sum;



	add_positive(&cfs_rq->avg.load_avg, delta);

	cfs_rq->avg.load_sum = cfs_rq->avg.load_avg * divider;

	se->avg.load_sum = runnable_sum;

	se->avg.load_avg = load_avg;

	add_positive(&cfs_rq->avg.load_avg, delta_avg);

	add_positive(&cfs_rq->avg.load_sum, delta_sum);

	/* See update_cfs_rq_load_avg() */

	cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,

					  cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);

}



static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum)
@@ -3687,7 +3693,9 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) 


		r = removed_load;

		sub_positive(&sa->load_avg, r);

		sa->load_sum = sa->load_avg * divider;

		sub_positive(&sa->load_sum, r * divider);

		/* See sa->util_sum below */

		sa->load_sum = max_t(u32, sa->load_sum, sa->load_avg * PELT_MIN_DIVIDER);



		r = removed_util;

		sub_positive(&sa->util_avg, r);