Re: [PATCH 04/16] sched/fair: Optimize find_idlest_cpu() when there is no choice

From	Mike Galbraith <umgwanakikbuti@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 04/16] sched/fair: Optimize find_idlest_cpu() when there is no choice
Date	2016-05-24 10:20 +0200
Message-ID	<rCfJf-OC-7@gated-at.bofh.it> (permalink)
References	<rBVKx-4Lf-3@gated-at.bofh.it> <rBVUe-53H-23@gated-at.bofh.it> <rCe0N-89R-9@gated-at.bofh.it> <rCfzA-Ln-11@gated-at.bofh.it>
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On Tue, 2016-05-24 at 09:05 +0100, Morten Rasmussen wrote:
> On Tue, May 24, 2016 at 08:29:05AM +0200, Mike Galbraith wrote:
> >  
> > > +> > > > 	> > > > /* Check if we have any choice */
> > > +> > > > 	> > > > if (group->group_weight == 1) {
> > > +> > > > 	> > > > > > > 	> > > > return cpumask_first(sched_group_cpus(group));
> > > +> > > > 	> > > > }
> > > +
> > 
> > Hm, if task isn't allowed there, too bad?
> 
> Is that possible for single-cpu groups? I thought we skipped groups with
> no cpus allowed in find_idlest_group():
> 
>                 /* Skip over this group if it has no CPUs allowed */
>                 if (!cpumask_intersects(sched_group_cpus(group),
>                                         tsk_cpus_allowed(p)))
>                         continue;
> 
> Since the group has at least one cpu allowed and only contains one cpu,
> that cpu must be allowed. No?

Yup, you're right, handled before we got there.

	-Mike

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[PATCH 04/16] sched/fair: Optimize find_idlest_cpu() when there is no choice Morten Rasmussen <morten.rasmussen@arm.com> - 2016-05-23 13:10 +0200
  Re: [PATCH 04/16] sched/fair: Optimize find_idlest_cpu() when there  is no choice Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-05-24 08:30 +0200
    Re: [PATCH 04/16] sched/fair: Optimize find_idlest_cpu() when there  is no choice Morten Rasmussen <morten.rasmussen@arm.com> - 2016-05-24 10:10 +0200
      Re: [PATCH 04/16] sched/fair: Optimize find_idlest_cpu() when there  is no choice Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-05-24 10:20 +0200

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