linux-kernel - Re: [PATCH v2 1/2] sched/schedutil: rework performance estimation

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Date:   Thu, 2 Nov 2023 13:58:46 +0100
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Dietmar Eggemann <dietmar.eggemann@....com>
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, rafael@...nel.org,
        viresh.kumar@...aro.org, qyousef@...alina.io,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        lukasz.luba@....com, wyes.karny@....com, beata.michalska@....com
Subject: Re: [PATCH v2 1/2] sched/schedutil: rework performance estimation

On Thu, 2 Nov 2023 at 13:03, Dietmar Eggemann <dietmar.eggemann@....com> wrote:
>
> On 26/10/2023 19:09, Vincent Guittot wrote:
>
> [...]
>
> > @@ -153,14 +152,38 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy,
> >       return cpufreq_driver_resolve_freq(policy, freq);
> >  }
> >
> > +unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual,
> > +                              unsigned long min,
> > +                              unsigned long max)
> > +{
> > +     unsigned long target;
> > +     struct rq *rq = cpu_rq(cpu);
> > +
> > +     if (rt_rq_is_runnable(&rq->rt))
> > +             return max;
> > +
> > +     /* Provide at least enough capacity for DL + IRQ */
> > +     target = min;
> > +
> > +     actual = map_util_perf(actual);
> > +     /* Actually we don't need to target the max performance */
> > +     if (actual < max)
> > +             max = actual;
> > +
> > +     /*
> > +      * Ensure at least minimum performance while providing more compute
> > +      * capacity when possible.
> > +      */
> > +     return max(target, max);
>
> The superfluous `unsigned long target` is still there?

Yeah, I forgot to add the change in this version but it's in the next one

>
>   return max(min, max) is much cleaer.
>
> [...]