Messages in this thread Patch in this message | | | From | Abel Wu <> | Subject | [PATCH v5 3/5] sched/fair: Skip core update if task pending | Date | Fri, 9 Sep 2022 13:53:02 +0800 |
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The function __update_idle_core() considers this cpu is idle so only checks its siblings to decide whether the resident core is idle or not and update has_idle_cores hint if necessary. But the problem is that this cpu might not be idle at that moment any more, resulting in the hint being misleading.
It's not proper to make this check everywhere in the idle path, but checking just before core updating can make the has_idle_core hint more reliable with negligible cost.
Signed-off-by: Abel Wu <wuyun.abel@bytedance.com> --- kernel/sched/fair.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7abe188a1533..fad289530e07 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6294,6 +6294,9 @@ void __update_idle_core(struct rq *rq) int core = cpu_of(rq); int cpu; + if (rq->ttwu_pending) + return; + rcu_read_lock(); if (test_idle_cores(core, true)) goto unlock; -- 2.37.3
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