From a6ec67b2fced9183665ccd69bd3751560095f0cd Mon Sep 17 00:00:00 2001 From: Qais Yousef Date: Mon, 2 Mar 2020 13:27:20 +0000 Subject: [PATCH] UPSTREAM: sched/rt: Remove unnecessary push for unfit tasks In task_woken_rt() and switched_to_rto() we try trigger push-pull if the task is unfit. But the logic is found lacking because if the task was the only one running on the CPU, then rt_rq is not in overloaded state and won't trigger a push. The necessity of this logic was under a debate as well, a summary of the discussion can be found in the following thread: https://lore.kernel.org/lkml/20200226160247.iqvdakiqbakk2llz@e107158-lin.cambridge.arm.com/ Remove the logic for now until a better approach is agreed upon. Bug: 120440300 Signed-off-by: Qais Yousef Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Fixes: 804d402fb6f6 ("sched/rt: Make RT capacity-aware") Link: https://lkml.kernel.org/r/20200302132721.8353-6-qais.yousef@arm.com (cherry picked from commit d94a9df49069ba8ff7c4aaeca1229e6471a01a15) Signed-off-by: Qais Yousef Change-Id: Ia49173b7be5dbd95e41cb1ddf248760975ad3355 --- kernel/sched/rt.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 973332cedd2d..6afc86f99a37 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2228,7 +2228,7 @@ static void task_woken_rt(struct rq *rq, struct task_struct *p) (rq->curr->nr_cpus_allowed < 2 || rq->curr->prio <= p->prio); - if (need_to_push || !rt_task_fits_capacity(p, cpu_of(rq))) + if (need_to_push) push_rt_tasks(rq); } @@ -2300,10 +2300,7 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p) */ if (task_on_rq_queued(p) && rq->curr != p) { #ifdef CONFIG_SMP - bool need_to_push = rq->rt.overloaded || - !rt_task_fits_capacity(p, cpu_of(rq)); - - if (p->nr_cpus_allowed > 1 && need_to_push) + if (p->nr_cpus_allowed > 1 && rq->rt.overloaded) rt_queue_push_tasks(rq); #endif /* CONFIG_SMP */ if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq)))