[tip: sched/urgent] sched/fair: Sync load_sum with load_avg after dequeue

[tip-bot2 for Vincent Guittot]

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     ceb6ba45dc8074d2a1ec1117463dc94a20d4203d
Gitweb:        https://git.kernel.org/tip/ceb6ba45dc8074d2a1ec1117463dc94a20d4203d
Author:        Vincent Guittot <vincent.guittot@xxxxxxxxxx>
AuthorDate:    Thu, 01 Jul 2021 19:18:37 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 02 Jul 2021 15:58:23 +02:00

sched/fair: Sync load_sum with load_avg after dequeue

commit 9e077b52d86a ("sched/pelt: Check that *_avg are null when *_sum are")
reported some inconsitencies between *_avg and *_sum.

commit 1c35b07e6d39 ("sched/fair: Ensure _sum and _avg values stay consistent")
fixed some but one remains when dequeuing load.

sync the cfs's load_sum with its load_avg after dequeuing the load of a
sched_entity.

Fixes: 9e077b52d86a ("sched/pelt: Check that *_avg are null when *_sum are")
Reported-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Odin Ugedal <odin@xxxxxxx>
Tested-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210701171837.32156-1-vincent.guittot@xxxxxxxxxx
---
 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 45edf61..1e263c9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3037,8 +3037,9 @@ enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
 static inline void
 dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
+	u32 divider = get_pelt_divider(&se->avg);
 	sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
-	sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum);
+	cfs_rq->avg.load_sum = cfs_rq->avg.load_avg * divider;
 }
 #else
 static inline void