Re: [PATCH 1/6 v3] sched/fair: Set next buddy for preempt short

[Peter Zijlstra]

On Thu, Jun 25, 2026 at 02:40:34PM +0200, Vincent Guittot wrote:
> On Thu, 25 Jun 2026 at 08:24, K Prateek Nayak <kprateek.nayak@xxxxxxx> wrote:
> >
> > Hello Vincent,
> >
> > On 6/24/2026 8:42 PM, Vincent Guittot wrote:
> > > 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);
> > >       }
> >
> > On a tangential note, I just noticed set_preempt_buddy() has two unused
> > parameters. Seems to have been like that since it was introduced in
> > commit e837456fdca8 ("sched/fair: Reimplement NEXT_BUDDY to align with
> > EEVDF goals").
> >
> > Perhaps this can be included in the series too as a cleanup:
> 
> I would even go further and remove it. The NEXT_BUDDY feature is broken anyway

I thought Mel wanted to try again, but he's been somewhat silent on
matters. Mel?