linux-kernel - Re: [PATCH v9 12/16] sched/core: uclamp: Extend CPU's cgroup controller

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Message-ID: <20190603122422.GA19426@darkstar>
Date:   Mon, 3 Jun 2019 13:24:22 +0100
From:   Patrick Bellasi <patrick.bellasi@....com>
To:     Tejun Heo <tj@...nel.org>, 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>,
        "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 v9 12/16] sched/core: uclamp: Extend CPU's cgroup
 controller

On 31-May 08:35, Tejun Heo wrote:
> Hello, Patrick.

Hi Tejun!

> On Wed, May 15, 2019 at 10:44:55AM +0100, Patrick Bellasi wrote:
> > Extend the CPU controller with a couple of new attributes util.{min,max}
> > which allows to enforce utilization boosting and capping for all the
> > tasks in a group. Specifically:
> > 
> > - util.min: defines the minimum utilization which should be considered
> > 	    i.e. the RUNNABLE tasks of this group will run at least at a
> > 		 minimum frequency which corresponds to the util.min
> > 		 utilization
> > 
> > - util.max: defines the maximum utilization which should be considered
> > 	    i.e. the RUNNABLE tasks of this group will run up to a
> > 		 maximum frequency which corresponds to the util.max
> > 		 utilization
> 
> Let's please use a prefix which is more specific.  It's clamping the
> utilization estimates of the member tasks which in turn affect
> scheduling / frequency decisions but cpu.util.max reads like it's
> gonna limit the cpu utilization directly.  Maybe just use uclamp?

Being too specific does not risk to expose implementation details?

If that's not a problem and Peter likes:

   cpu.uclamp.{min,max}

that's ok with me.

-- 
#include <best/regards.h>

Patrick Bellasi