This is a note to let you know that I've just added the patch titled
sched/fair: Fix overutilized update in enqueue_task_fair()
to the 5.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-fair-fix-overutilized-update-in-enqueue_task_f.patch
and it can be found in the queue-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f6cdb95dde5ba6b04d7c89a121d1f041c4806baa
Author: Quentin Perret <qperret@xxxxxxxxxx>
Date: Thu Nov 12 11:12:01 2020 +0000
sched/fair: Fix overutilized update in enqueue_task_fair()
[ 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@xxxxxxxxxx>
Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Reviewed-by: Valentin Schneider <valentin.schneider@xxxxxxx>
Link: https://lkml.kernel.org/r/20201112111201.2081902-1-qperret@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 48a6d442b4443..c0c4d9ad7da8e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5473,6 +5473,7 @@ 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
@@ -5545,7 +5546,7 @@ 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);
enqueue_throttle:
