From: Quentin Perret <qperret@google.com>
To: stable@vger.kernel.org, gregkh@linuxfoundation.org, sashal@kernel.org
Cc: Quentin Perret <qperret@google.com>,
Rick Yiu <rickyiu@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Valentin Schneider <valentin.schneider@arm.com>
Subject: [PATCH 5.4] sched/fair: Fix overutilized update in enqueue_task_fair()
Date: Mon, 23 Nov 2020 10:18:27 +0000 [thread overview]
Message-ID: <20201123101827.451304-1-qperret@google.com> (raw)
[ Upstream commit 8e1ac4299a6e8726de42310d9c1379f188140c71 ]
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: 2802bf3cd936 ("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
---
kernel/sched/fair.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index dddaf61378f6..200e12110109 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5228,6 +5228,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
int idle_h_nr_running = task_has_idle_policy(p);
+ int task_new = !(flags & ENQUEUE_WAKEUP);
/*
* The code below (indirectly) updates schedutil which looks at
@@ -5299,7 +5300,7 @@ 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);
}
--
2.29.2.454.gaff20da3a2-goog
next reply other threads:[~2020-11-23 10:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-23 10:18 Quentin Perret [this message]
2020-11-23 11:30 ` [PATCH 5.4] sched/fair: Fix overutilized update in enqueue_task_fair() Greg KH
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