This is a note to let you know that I've just added the patch titled
sched/fair: remove util_est boosting
to the 6.5-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-remove-util_est-boosting.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8321f873118546d471373231a277665924afedeb
Author: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Date: Thu Jul 6 15:51:44 2023 +0200
sched/fair: remove util_est boosting
[ Upstream commit c2e164ac33f75e0acb93004960c73bd9166d3d35 ]
There is no need to use runnable_avg when estimating util_est and that
even generates wrong behavior because one includes blocked tasks whereas
the other one doesn't. This can lead to accounting twice the waking task p,
once with the blocked runnable_avg and another one when adding its
util_est.
cpu's runnable_avg is already used when computing util_avg which is then
compared with util_est.
In some situation, feec will not select prev_cpu but another one on the
same performance domain because of higher max_util
Fixes: 7d0583cf9ec7 ("sched/fair, cpufreq: Introduce 'runnable boosting'")
Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Tested-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Link: https://lore.kernel.org/r/20230706135144.324311-1-vincent.guittot@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b3e25be58e2b7..1d9c2482c5a35 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7289,9 +7289,6 @@ cpu_util(int cpu, struct task_struct *p, int dst_cpu, int boost)
util_est = READ_ONCE(cfs_rq->avg.util_est.enqueued);
- if (boost)
- util_est = max(util_est, runnable);
-
/*
* During wake-up @p isn't enqueued yet and doesn't contribute
* to any cpu_rq(cpu)->cfs.avg.util_est.enqueued.
