Commit b9c88f75 authored Oct 15, 2020 by jun qian Committed by Peter Zijlstra Oct 29, 2020

sched/fair: Improve the accuracy of sched_stat_wait statistics



When the sched_schedstat changes from 0 to 1, some sched se maybe
already in the runqueue, the se->statistics.wait_start will be 0.
So it will let the (rq_of(cfs_rq)) - se->statistics.wait_start)
wrong. We need to avoid this scenario.

Signed-off-by: jun qian <qianjun.kernel@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lkml.kernel.org/r/20201015064846.19809-1-qianjun.kernel@gmail.com

parent 23859ae4

kernel/sched/fair.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -906,6 +906,15 @@ update_stats_wait_end(struct cfs_rq cfs_rq, struct sched_entity se)
		if (!schedstat_enabled())
		return;

		/*
		* When the sched_schedstat changes from 0 to 1, some sched se
		* maybe already in the runqueue, the se->statistics.wait_start
		* will be 0.So it will let the delta wrong. We need to avoid this
		* scenario.
		*/
		if (unlikely(!schedstat_val(se->statistics.wait_start)))
		return;

		delta = rq_clock(rq_of(cfs_rq)) - schedstat_val(se->statistics.wait_start);

		if (entity_is_task(se)) {

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