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From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: mingo@redhat.com, juri.lelli@redhat.com,
	dietmar.eggemann@arm.com, rostedt@goodmis.org,
	bsegall@google.com, mgorman@suse.de, vschneid@redhat.com,
	kprateek.nayak@amd.com, linux-kernel@vger.kernel.org,
	qyousef@layalina.io
Subject: Re: [PATCH 1/6 v2] sched/fair: Set next buddy for preempt short
Date: Tue, 16 Jun 2026 10:51:54 +0200	[thread overview]
Message-ID: <20260616085154.GG42921@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20260615162420.420957-2-vincent.guittot@linaro.org>

On Mon, Jun 15, 2026 at 06:24:15PM +0200, Vincent Guittot wrote:
> If a shorter slice task can preempt current at wakeup, we make sure that
> the decision will not be overwritten in between by setting the task as the
> next buddy. This still implies that the waking task remains eligible when
> the scheduler will actually pick the next task to run.
> 
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> ---
>  kernel/sched/fair.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index d78467ec6ee1..83bce5a04f3d 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -9903,7 +9903,7 @@ static void wakeup_preempt_fair(struct rq *rq, struct task_struct *p, int wake_f
>  preempt:
>  	if (preempt_action == PREEMPT_WAKEUP_SHORT) {
>  		cancel_protect_slice(se);
> -		clear_buddies(cfs_rq, se);
> +		set_next_buddy(&p->se);
>  	}

Should this not be something along the lines of set_preempt_buddy()?

  reply	other threads:[~2026-06-16  8:52 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-15 16:24 [PATCH 0/6 v2] sched/eevdf: Improve scheduling latency of short slice task Vincent Guittot
2026-06-15 16:24 ` [PATCH 1/6 v2] sched/fair: Set next buddy for preempt short Vincent Guittot
2026-06-16  8:51   ` Peter Zijlstra [this message]
2026-06-16 13:52     ` Vincent Guittot
2026-06-15 16:24 ` [PATCH 2/6 v2] sched/eevdf: Take into account current's lag when updating slice protection Vincent Guittot
2026-06-16  3:52   ` K Prateek Nayak
2026-06-16 12:11     ` Vincent Guittot
2026-06-16  9:29   ` Peter Zijlstra
2026-06-16 12:49     ` Vincent Guittot
2026-06-15 16:24 ` [PATCH 3/6 v2] sched/eevdf: Update slice protection even when resched is already set Vincent Guittot
2026-06-16  9:37   ` Peter Zijlstra
2026-06-16 13:57     ` Vincent Guittot
2026-06-15 16:24 ` [PATCH 4/6 v2] sched/eevdf: Cancel slice protection if short slice task is eligible Vincent Guittot
2026-06-16  5:34   ` K Prateek Nayak
2026-06-16 12:51     ` Vincent Guittot
2026-06-15 16:24 ` [PATCH 5/6 v2] sched/eevdf: Always update slice protection Vincent Guittot
2026-06-15 16:24 ` [PATCH 6/6 v2] sched/eevdf: Speedup short slice task scheduling Vincent Guittot
2026-06-16 10:57   ` Peter Zijlstra
2026-06-16 15:18     ` Vincent Guittot
2026-06-17 16:01       ` Vincent Guittot
2026-06-16  7:43 ` [PATCH 0/6 v2] sched/eevdf: Improve scheduling latency of short slice task K Prateek Nayak
2026-06-16 13:58   ` Vincent Guittot

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