Re: Re: [PATCH 1/2] sched/fair: Do not let idle entities preempt others

[Abel Wu]

On 2/23/25 1:48 AM, Madadi Vineeth Reddy Wrote:
> On 21/02/25 16:42, Abel Wu wrote:
> > A task with SCHED_IDLE policy doesn't preempt others by definition, and
> > the semantics are intended to be preserved when extending to cgroups
> > introduced in commit 304000390f88 ("sched: Cgroup SCHED_IDLE support").
>
> [snip]
>
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 1c0ef435a7aa..4340178f29b7 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -8778,12 +8778,15 @@ static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int
> >   	pse_is_idle = se_is_idle(pse);
> >   
> >   	/*
> > -	 * Preempt an idle entity in favor of a non-idle entity (and don't preempt
> > -	 * in the inverse case).
> > +	 * Preempt an idle entity in favor of a non-idle entity.
> >   	 */
> >   	if (cse_is_idle && !pse_is_idle)
> >   		goto preempt;
>
> This patch doesn't apply cleanly on top of tip/sched/core because of the
> commit f553741ac8c0 ("sched: Cancel the slice protection of the idle entity").
> Please rebase it.

Will rebase. Thanks!

> Thanks,
> Madadi Vineeth Reddy
>
> > -	if (cse_is_idle != pse_is_idle)
> > +
> > +	/*
> > +	 * IDLE entities do not preempt others.
> > +	 */
> > +	if (unlikely(pse_is_idle))
> >   		return;
> >   
> >   	/*