linux-kernel - Re: [PATCH] sched: Increase sched_tick

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Message-ID: <124838f6-8cee-422a-b877-82ad98879d0a@huawei.com>
Date: Tue, 16 Sep 2025 16:44:39 +0800
From: "wangtao (EQ)" <wangtao554@...wei.com>
To: Phil Auld <pauld@...hat.com>, <frederic@...nel.org>
CC: <bsegall@...gle.com>, <dietmar.eggemann@....com>, <juri.lelli@...hat.com>,
	<linux-kernel@...r.kernel.org>, <mgorman@...e.de>, <mingo@...hat.com>,
	<peterz@...radead.org>, <rostedt@...dmis.org>, <tanghui20@...wei.com>,
	<tglx@...utronix.de>, <vincent.guittot@...aro.org>, <zhangqiao22@...wei.com>,
	Waiman Long <longman@...hat.com>
Subject: Re: [PATCH] sched: Increase sched_tick_remote timeout

Increasing timeout alerts can reduce the probability of deadlocks. However, in the 'sched_tick_remote' method, there are 'WARN_ON_ONCE(rq->curr!= rq->donor)' and 'assert_clock_updated' in 'rq_clock_task'. Regardless of why these alerts are triggered, once they are triggered, 'printk' is called, which still leaves potential deadlock issues. Is there a better way to address these problems?

在 2025/9/12 0:13, Phil Auld 写道:
> Increase the sched_tick_remote WARN_ON timeout to remove false
> positives due to temporarily busy HK cpus. The suggestion
> was 30 seconds to catch really stuck remote tick processing
> but not trigger it too easily.
>
> Signed-off-by: Phil Auld <pauld@...hat.com>
> Suggested-by: Frederic Weisbecker <frederic@...nel.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Frederic Weisbecker <frederic@...nel.org>
> ---
>   kernel/sched/core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index be00629f0ba4..ef90d358252d 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5724,7 +5724,7 @@ static void sched_tick_remote(struct work_struct *work)
>   				 * reasonable amount of time.
>   				 */
>   				u64 delta = rq_clock_task(rq) - curr->se.exec_start;
> -				WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
> +				WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 30);
>   			}
>   			curr->sched_class->task_tick(rq, curr, 0);
>