linux-kernel - Re: [Patch v4 3/6] sched/fair: Enable CFS periodic tick to update thermal pressure

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Message-ID: <20191028152735.GC5671@hirez.programming.kicks-ass.net>
Date:   Mon, 28 Oct 2019 16:27:35 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     mingo@...hat.com, ionela.voinescu@....com,
        vincent.guittot@...aro.org, rui.zhang@...el.com,
        edubezval@...il.com, qperret@...gle.com,
        linux-kernel@...r.kernel.org, amit.kachhap@...il.com,
        javi.merino@...nel.org, daniel.lezcano@...aro.org
Subject: Re: [Patch v4 3/6] sched/fair: Enable CFS periodic tick to update
 thermal pressure

On Mon, Oct 28, 2019 at 04:24:21PM +0100, Peter Zijlstra wrote:
> On Tue, Oct 22, 2019 at 04:34:22PM -0400, Thara Gopinath wrote:
> > Introduce support in CFS periodic tick to trigger the process of
> > computing average thermal pressure for a cpu.
> > 
> > Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
> > ---
> >  kernel/sched/fair.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 682a754..4f9c2cb 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -21,6 +21,7 @@
> >   *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
> >   */
> >  #include "sched.h"
> > +#include "thermal.h"
> >  
> >  #include <trace/events/sched.h>
> >  
> > @@ -7574,6 +7575,8 @@ static void update_blocked_averages(int cpu)
> >  		done = false;
> >  
> >  	update_blocked_load_status(rq, !done);
> > +
> > +	trigger_thermal_pressure_average(rq);
> >  	rq_unlock_irqrestore(rq, &rf);
> >  }
> 
> This changes only 1 of the 2 implementations of
> update_blocked_averages(). Also, how does this interact with
> rq->has_blocked_load ?

Specifically, I'm thikning this wants a line in others_have_blocked():

+	if (READ_ONCE(rq->avg_thermal.load_avg))
+		return true;