linux-kernel - Re: [PATCH v4 6/6] sched/fair: Consider SMT in ASYM

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Message-ID: <CAKfTPtAKYyy4asSBEcv3=1KWXWvDafrv=A_rh6BR9MgY17WdXA@mail.gmail.com>
Date:   Sat, 28 Aug 2021 15:25:56 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Len Brown <len.brown@...el.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Ricardo Neri <ricardo.neri@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Quentin Perret <qperret@...gle.com>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        linuxppc-dev@...ts.ozlabs.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Aubrey Li <aubrey.li@...el.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>
Subject: Re: [PATCH v4 6/6] sched/fair: Consider SMT in ASYM_PACKING load balance

On Fri, 27 Aug 2021 at 21:45, Ricardo Neri
<ricardo.neri-calderon@...ux.intel.com> wrote:
>
> On Fri, Aug 27, 2021 at 12:13:42PM +0200, Vincent Guittot wrote:
> > On Tue, 10 Aug 2021 at 16:41, Ricardo Neri
> > <ricardo.neri-calderon@...ux.intel.com> wrote:
> > > @@ -9540,6 +9629,12 @@ static struct rq *find_busiest_queue(struct lb_env *env,
> > >                     nr_running == 1)
> > >                         continue;
> > >
> > > +               /* Make sure we only pull tasks from a CPU of lower priority */
> > > +               if ((env->sd->flags & SD_ASYM_PACKING) &&
> > > +                   sched_asym_prefer(i, env->dst_cpu) &&
> > > +                   nr_running == 1)
> > > +                       continue;
> >
> > This really looks similar to the test above for SD_ASYM_CPUCAPACITY.
> > More generally speaking SD_ASYM_PACKING and SD_ASYM_CPUCAPACITY share
> > a lot of common policy and I wonder if at some point we could not
> > merge their behavior in LB
>
> I would like to confirm with you that you are not expecting this merge
> as part of this series, right?

Merging them will probably need more tests on both x86 and Arm so I
suppose that we could keep them separate for now

Regards,
Vincent

>
> Thanks and BR,
> Ricardo