From: Vincent Guittot Date: Tue, 11 Jul 2023 08:13:59 +0000 (+0200) Subject: sched/fair: Stabilize asym cpu capacity system idle cpu selection X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7ee7642c91410fb90cc45e799a3a46e1607ecd79;p=linux.git sched/fair: Stabilize asym cpu capacity system idle cpu selection select_idle_capacity() not only looks for an idle cpu that fits for the waking task but also for cpu with highest bandwidth when no cpu fits. Start the loop with target cpu so it will be selected 1st when no cpu fits but several cpus shared the same bandwidth. Starting with target cpu prevents the task to migrate between cpus with same bandwidth at every wakeup when no cpu fits. Signed-off-by: Vincent Guittot Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230711081359.868862-1-vincent.guittot@linaro.org --- diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index a87988327f88..0cd1cdbae534 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7096,7 +7096,7 @@ select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int target) util_min = uclamp_eff_value(p, UCLAMP_MIN); util_max = uclamp_eff_value(p, UCLAMP_MAX); - for_each_cpu_wrap(cpu, cpus, target + 1) { + for_each_cpu_wrap(cpu, cpus, target) { unsigned long cpu_cap = capacity_of(cpu); if (!available_idle_cpu(cpu) && !sched_idle_cpu(cpu))