linux-kernel - Re: [RFC][PATCH v2 2/2] cpufreq: schedutil: Avoid decreasing frequency of busy CPUs

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Date:   Tue, 21 Mar 2017 16:04:03 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Patrick Bellasi <patrick.bellasi@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Juri Lelli <juri.lelli@....com>,
        Joel Fernandes <joelaf@...gle.com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [RFC][PATCH v2 2/2] cpufreq: schedutil: Avoid decreasing
 frequency of busy CPUs

On Tue, Mar 21, 2017 at 03:46:07PM +0100, Rafael J. Wysocki wrote:
> @@ -207,6 +212,8 @@ static void sugov_update_single(struct u
>  	if (!sugov_should_update_freq(sg_policy, time))
>  		return;
>  
> +	sg_policy->overload = this_rq()->rd->overload;
> +

Same problem as before; rd->overload is set if _any_ CPU in the root
domain has more than 1 runnable task at a random point in history (when
we ran the load balance tick -- and since that is the same tick used for
timers, there's a bias to over-account there).