Re: [PATCH 1/6 v2] sched/fair: Set next buddy for preempt short

[Peter Zijlstra]

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@xxxxxxxxxx>
> ---
>  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()?