linux-kernel - Re: [PATCH v3 0/6] cpufreq: schedutil: fixes for flags updates

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Message-ID: <20171220181608.ztar2d5vrthclhc5@hirez.programming.kicks-ass.net>
Date:   Wed, 20 Dec 2017 19:16:08 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Juri Lelli <juri.lelli@...hat.com>
Cc:     Patrick Bellasi <patrick.bellasi@....com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Ingo Molnar <mingo@...hat.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Todd Kjos <tkjos@...roid.com>,
        Joel Fernandes <joelaf@...gle.com>
Subject: Re: [PATCH v3 0/6] cpufreq: schedutil: fixes for flags updates

On Wed, Dec 20, 2017 at 06:38:14PM +0100, Juri Lelli wrote:
> On 20/12/17 16:30, Peter Zijlstra wrote:
> 
> [...]
> 
> > @@ -327,12 +331,7 @@ static unsigned int sugov_next_freq_shar
> >  		if (delta_ns > TICK_NSEC) {
> >  			j_sg_cpu->iowait_boost = 0;
> >  			j_sg_cpu->iowait_boost_pending = false;
> > -			j_sg_cpu->util_cfs = 0;
> > -			if (j_sg_cpu->util_dl == 0)
> > -				continue;
> >  		}
> 
> This goes away because with Brendan/Vincent fix we don't need the
> workaround for stale CFS util contribution for idle CPUs anymore?

Oh, good point, no I took that out because of:

@@ -314,6 +315,9 @@ static unsigned int sugov_next_freq_shar

                unsigned long j_util, j_max;
                s64 delta_ns;

+               if (j_sg_cpu != sg_cpu)
+                       sugov_get_util(j_sg_cpu);
+
                /*
                 * If the CFS CPU utilization was last updated before the
                 * previous frequency update and the time elapsed between the


which recomputes the util value all the time. But yes, that still needs
those other patches to stay relevant.