Re: [PATCH] sched/fair: Restart hrtick after same-task repicks

[Peter Zijlstra]

On Fri, Sep 11, 2026 at 02:36:41PM +0200, Vincent Guittot wrote:

> > @@ -15293,11 +15297,12 @@ static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first)
> >
> >         WARN_ON_ONCE(se->sched_delayed);
> >
> > -       if (hrtick_enabled_fair(rq))
> > -               hrtick_start_fair(rq, p);
> > -
> >         update_misfit_status(p, rq);
> >         sched_fair_update_stop_tick(rq, p);
> > +
> > +repick:
> > +       if (hrtick_enabled_fair(rq))
> > +               hrtick_start_fair(rq, p);
> 
> While at it, you might want to replace:
> vdelta = se->deadline - se->vruntime;
> by
> vdelta = se->vprot - se->vruntime;
> in hrtick_start_fair()

That should be a separate patch.

> 
> >  }
> >
> >  void init_cfs_rq(struct cfs_rq *cfs_rq)

But that made me thing; do we want something like so folded in here?

Since we got picked again, we should set vprot again, no?

---
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -15279,11 +15279,8 @@ static void set_next_task_fair(struct rq
 	se = &p->se;
 	cfs_rq->curr = se;
 
-	if (on_rq) {
+	if (on_rq)
 		reweight_eevdf(cfs_rq, se, weight, se->on_rq);
-		if (first)
-			set_protect_slice(cfs_rq, se);
-	}
 
 	if (task_on_rq_queued(p)) {
 		/*
@@ -15301,6 +15298,9 @@ static void set_next_task_fair(struct rq
 	sched_fair_update_stop_tick(rq, p);
 
 repick:
+	if (on_rq)
+		set_protect_slice(cfs_rq, se);
+
 	if (hrtick_enabled_fair(rq))
 		hrtick_start_fair(rq, p);
 }