From 444683e9df5852431539e1814df912759cf80370 Mon Sep 17 00:00:00 2001 From: Quentin Perret Date: Thu, 12 Nov 2020 11:12:01 +0000 Subject: [PATCH] BACKPORT: 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 Signed-off-by: Quentin Perret Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vincent Guittot Reviewed-by: Valentin Schneider Link: https://lkml.kernel.org/r/20201112111201.2081902-1-qperret@google.com Change-Id: I04a99c7db2d0559e838343762a928ac6caa1a9c4 --- 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 7f7fa1a2ee32..14c863e52bfe 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -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); }