linux-kernel - Re: [Eas-dev] [PATCH V4 0/3] sched: cpufreq: Allow remote callbacks

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Message-ID: <20170727072146.uiuvadgsbpjk5gyb@e106622-lin>
Date:   Thu, 27 Jul 2017 08:21:46 +0100
From:   Juri Lelli <juri.lelli@....com>
To:     "Joel Fernandes (Google)" <joel.opensrc@...il.com>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Joel Fernandes <joelaf@...gle.com>, eas-dev@...ts.linaro.org,
        linux-pm@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        smuckle.linux@...il.com, Len Brown <lenb@...nel.org>
Subject: Re: [Eas-dev] [PATCH V4 0/3] sched: cpufreq: Allow remote callbacks

Hi,

On 26/07/17 23:23, Joel Fernandes (Google) wrote:
> Hi Viresh,
> 
> On Wed, Jul 26, 2017 at 10:46 PM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> > On 26-07-17, 22:14, Joel Fernandes (Google) wrote:

[...]

> >
> > But even without that, if you see the routine
> > init_entity_runnable_average() in fair.c, the new tasks are
> > initialized in a way that they are seen as heavy tasks. And so even
> > for the first time they run, freq should normally increase on the
> > target CPU (at least with above application).i
> 
> Ok, but the "heavy" in init_entity_runnable_average means for load,
> not the util_avg. The util_avg is what's used for frequency scaling
> IIUC and is set to 0 in that function no?
> 

True for init_entity_runnable_average(), but for new task post_init_
entity_util_avg() is then also called (from wake_up_new_task()), which
modifies the initial util_avg value (depending on current rq {util,
load}_avg.