linux-kernel - Re: [PATCH v6 09/16] sched/cpufreq: uclamp: Add utilization clamping for RT tasks

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Message-ID: <20190123143327.whlyx2223xzchbkl@e110439-lin>
Date:   Wed, 23 Jan 2019 14:33:27 +0000
From:   Patrick Bellasi <patrick.bellasi@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-api@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Tejun Heo <tj@...nel.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Paul Turner <pjt@...gle.com>,
        Quentin Perret <quentin.perret@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Todd Kjos <tkjos@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Steve Muckle <smuckle@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>
Subject: Re: [PATCH v6 09/16] sched/cpufreq: uclamp: Add utilization clamping
 for RT tasks

On 23-Jan 11:28, Peter Zijlstra wrote:
> On Tue, Jan 15, 2019 at 10:15:06AM +0000, Patrick Bellasi wrote:
> > -	util = (type == ENERGY_UTIL)
> > -		? util_cfs
> > -		: uclamp_util(rq, util_cfs);
> > -	util += cpu_util_rt(rq);
> > +	util = cpu_util_rt(rq);
> > +	if (type == FREQUENCY_UTIL) {
> > +		util += cpu_util_cfs(rq);
> > +		util  = uclamp_util(rq, util);
> > +	} else {
> > +		util += util_cfs;
> > +	}
> 
> Or the combined thing:
> 
> -       util = util_cfs;
> -       util += cpu_util_rt(rq);
> +       util = cpu_util_rt(rq);
> +       if (type == FREQUENCY_UTIL) {
> +               util += cpu_util_cfs(rq);
> +               util  = uclamp_util(rq, util);
> +       } else {
> +               util += util_cfs;
> +       }
> 
> 
> Leaves me confused.
> 
> When type == FREQ, util_cfs should already be cpu_util_cfs(), per
> sugov_get_util().
> 
> So should that not end up like:
> 
> 	util = util_cfs;
> 	util += cpu_util_rt(rq);
> +	if (type == FREQUENCY_UTIL)
> +		util = uclamp_util(rq, util);
> 
> instead?

You right, I get to that core after the patches which integrate
compute_energy(). The chuck above was the version before the EM got
merged but I missed to backport the change once I rebased on
tip/sched/core with the EM in.

Sorry for the confusion, will fix in v7.

Cheers

-- 
#include <best/regards.h>

Patrick Bellasi