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BACKPORT: sched/fair: Fix overutilized update in enqueue_task_fair()

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[ Upstream commit 8e1ac4299a ]

enqueue_task_fair() attempts to skip the overutilized update for new
tasks as their util_avg is not accurate yet. However, the flag we check
to do so is overwritten earlier on in the function, which makes the
condition pretty much a nop.

Fix this by saving the flag early on.

Fixes: 2802bf3cd9 ("sched/fair: Add over-utilization/tipping point indicator")
Reported-by: Rick Yiu <rickyiu@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20201112111201.2081902-1-qperret@google.com
Change-Id: I04a99c7db2d0559e838343762a928ac6caa1a9c4
This commit is contained in:
Quentin Perret 2020-11-12 11:12:01 +00:00
parent f8d9d560b9
commit 444683e9df
1 changed files with 2 additions and 1 deletions
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3
kernel/sched/fair.c
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@ -5246,6 +5246,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
{
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
int task_new = !(flags & ENQUEUE_WAKEUP);
/*
* The code below (indirectly) updates schedutil which looks at
@ -5327,7 +5328,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
* into account, but that is not straightforward to implement,
* and the following generally works well enough in practice.
*/
if (flags & ENQUEUE_WAKEUP)
if (!task_new)
update_overutilized_status(rq);
}