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

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Date:   Wed, 5 Jun 2019 16:37:43 +0100
From:   Patrick Bellasi <patrick.bellasi@....com>
To:     Tejun Heo <tj@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-api@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.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 v9 12/16] sched/core: uclamp: Extend CPU's cgroup
 controller

On 05-Jun 07:44, Tejun Heo wrote:
> Hello,

Hi,

> On Wed, Jun 05, 2019 at 03:39:50PM +0100, Patrick Bellasi wrote:
> > Which means we will enforce the effective values as:
> > 
> >    /tg1/tg11:
> > 
> >          util_min.effective=0
> >             i.e. keep the child protection since smaller than parent
> > 
> >          util_max.effective=800
> >             i.e. keep parent limit since stricter than child
> >
> > Please shout if I got it wrong, otherwise I'll update v10 to
> > implement the above logic.
> 
> Everything sounds good to me.  Please note that cgroup interface files
> actually use literal "max" for limit/protection max settings so that 0
> and "max" mean the same things for all limit/protection knobs.

Lemme see if I've got it right, do you mean that we can:

 1) write the _string_ "max" into a cgroup attribute to:

    - set    0 for util_max, since it's a protection
    - set 1024 for util_min, since it's a limit

 2) write the _string_ "0" into a cgroup attribute to:

    - set 1024 for util_max, since it's a protection
    - set    0 for util_min, since it's a limit

Is that correct or it's just me totally confused?


> Thanks.
> 
> --
> tejun

Cheers,
Patrick

-- 
#include <best/regards.h>

Patrick Bellasi