From: Quentin Perret qperret@google.com
commit 8e1ac4299a6e8726de42310d9c1379f188140c71 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/sched/fair.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5228,6 +5228,7 @@ enqueue_task_fair(struct rq *rq, struct 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_throttle: * 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);
}