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sched/fair: Improve the accuracy of sched_stat_wait statistics

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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
This commit is contained in:
jun qian 2020-10-15 14:48:46 +08:00 committed by Peter Zijlstra
parent 23859ae444
commit b9c88f7522
1 changed files with 9 additions and 0 deletions
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9
kernel/sched/fair.c
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@ -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)) {