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Date:   Mon, 28 Oct 2019 16:30:10 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Qais Yousef <qais.yousef@arm.com>
Cc:     Thara Gopinath <thara.gopinath@linaro.org>, mingo@redhat.com,
        ionela.voinescu@arm.com, vincent.guittot@linaro.org,
        rui.zhang@intel.com, edubezval@gmail.com, qperret@google.com,
        linux-kernel@vger.kernel.org, amit.kachhap@gmail.com,
        javi.merino@kernel.org, daniel.lezcano@linaro.org
Subject: Re: [Patch v4 4/6] sched/fair: update cpu_capcity to reflect thermal
 pressure
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 <20191023122252.dz7obopab6iizy4s@e107158-lin.cambridge.arm.com>
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On Wed, Oct 23, 2019 at 01:28:40PM +0100, Qais Yousef wrote:
> On 10/22/19 16:34, Thara Gopinath wrote:
> > cpu_capacity relflects the maximum available capacity of a cpu. Thermal
> > pressure on a cpu means this maximum available capacity is reduced. This
> > patch reduces the average thermal pressure for a cpu from its maximum
> > available capacity so that cpu_capacity reflects the actual
> > available capacity.
> > 
> > Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
> > ---
> >  kernel/sched/fair.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 4f9c2cb..be3e802 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -7727,6 +7727,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu)
> >  
> >  	used = READ_ONCE(rq->avg_rt.util_avg);
> >  	used += READ_ONCE(rq->avg_dl.util_avg);
> > +	used += READ_ONCE(rq->avg_thermal.load_avg);
> 
> Maybe a naive question - but can we add util_avg with load_avg without
> a conversion? I thought the 2 signals have different properties.

Changelog of patch #1 explains, it's in that dense blob of text.

But yes, you're quite right that that wants a comment here.