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To: Steve Muckle <steve.muckle@linaro.org>, peterz@infradead.org,
        rjw@rjwysocki.net
From: Michael Turquette <mturquette@baylibre.com>
In-Reply-To: <56E8CA8B.8080506@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Juri.Lelli@arm.com,
        morten.rasmussen@arm.com, dietmar.eggemann@arm.com,
        vincent.guittot@linaro.org,
        "Michael Turquette" <mturquette+renesas@baylibre.com>
References: <1457932932-28444-1-git-send-email-mturquette+renesas@baylibre.com>
 <1457932932-28444-3-git-send-email-mturquette+renesas@baylibre.com>
 <56E8CA8B.8080506@linaro.org>
Message-ID: <20160316221236.11016.51095@quark.deferred.io>
User-Agent: alot/0.3.6
Subject: Re: [PATCH 2/8] sched/fair: add margin to utilization update
Date: Wed, 16 Mar 2016 15:12:36 -0700
Sender: linux-kernel-owner@vger.kernel.org
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Quoting Steve Muckle (2016-03-15 19:52:59)
> On 03/13/2016 10:22 PM, Michael Turquette wrote:
> > +unsigned long cfs_capacity_margin = CAPACITY_MARGIN_DEFAULT;
> > +
> >  #ifdef CONFIG_CFS_BANDWIDTH
> >  /*
> >   * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
> > @@ -2840,6 +2853,8 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg)
> >  
> >       if (cpu == smp_processor_id() && &rq->cfs == cfs_rq) {
> >               unsigned long max = rq->cpu_capacity_orig;
> > +             unsigned long cap = cfs_rq->avg.util_avg *
> > +                     cfs_capacity_margin / max;
> 
> Doesn't rq->cpu_capacity_orig get scaled per the microarch invariance?
> This would mean that the margin we're applying here would differ based
> on that.
> 
> I'd expect that the margin would be * (cfs_capacity_margin /
> SCHED_CAPACITY_SCALE) which would then reduce the division into a shift.

Will fix.

Thanks,
Mike