linux-kernel - Re: [PATCH 1/2] sched: cpufreq: ignore SMT when determining max cpu capacity

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Message-ID: <20160831143437.GW10121@twins.programming.kicks-ass.net>
Date:   Wed, 31 Aug 2016 16:34:37 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Steve Muckle <steve.muckle@...aro.org>,
        Ingo Molnar <mingo@...hat.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Juri Lelli <Juri.Lelli@....com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Steve Muckle <smuckle@...aro.org>
Subject: Re: [PATCH 1/2] sched: cpufreq: ignore SMT when determining max cpu
 capacity

On Wed, Aug 31, 2016 at 03:27:30AM +0200, Rafael J. Wysocki wrote:
> On Friday, August 26, 2016 11:40:47 AM Steve Muckle wrote:
> > PELT does not consider SMT when scaling its utilization values via
> > arch_scale_cpu_capacity(). The value in rq->cpu_capacity_orig does
> > take SMT into consideration though and therefore may be smaller than
> > the utilization reported by PELT.
> > 
> > On an Intel i7-3630QM for example rq->cpu_capacity_orig is 589 but
> > util_avg scales up to 1024. This means that a 50% utilized CPU will show
> > up in schedutil as ~86% busy.
> > 
> > Fix this by using the same CPU scaling value in schedutil as that which
> > is used by PELT.
> > 
> > Signed-off-by: Steve Muckle <smuckle@...aro.org>
> 
> This is fine by me.
> 
> Peter, any objections?

No, looks good. Thanks