linux-kernel - Re: [PATCH v2 01/12] sched/core: uclamp: extend sched

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Date:   Wed, 18 Jul 2018 09:42:18 +0100
From:   Patrick Bellasi <patrick.bellasi@....com>
To:     Joel Fernandes <joel@...lfernandes.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tejun Heo <tj@...nel.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Paul Turner <pjt@...gle.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 v2 01/12] sched/core: uclamp: extend sched_setattr to
 support utilization clamping

On 17-Jul 10:50, Joel Fernandes wrote:
> On Mon, Jul 16, 2018 at 09:28:55AM +0100, Patrick Bellasi wrote:

[...]

> > diff --git a/init/Kconfig b/init/Kconfig
> > index 041f3a022122..1d45a6877d6f 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -583,6 +583,25 @@ config HAVE_UNSTABLE_SCHED_CLOCK
> >  config GENERIC_SCHED_CLOCK
> >  	bool
> >  
> > +menu "Scheduler features"
> > +
> > +config UCLAMP_TASK
> > +	bool "Enable utilization clamping for RT/FAIR tasks"
> > +	depends on CPU_FREQ_GOV_SCHEDUTIL
> 
> Does it make sense to depend on this? One could turn off schedutil and then
> uclamp can't be used for any other purpose (big.LITTLE task placement etc)?

You right, utilization clamping is _going_ to target tasks placement.
But, the support currently posted in this series is just for OPP
biasing. Thus, it would not make sense to enabled it when schedutil
is not available.

My idea was to keep this dependency while we finalize these bits.
Once we move on to the tasks placement biasing, we will remove this
dependency too.

Does that makes sense?

> thanks,
> 
> - Joel

-- 
#include <best/regards.h>

Patrick Bellasi