linux-kernel - Re: [PATCH v4 03/16] sched/core: uclamp: add CPU's clamp groups accounting

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Message-ID: <20180912174456.GJ1413@e110439-lin>
Date:   Wed, 12 Sep 2018 18:44:56 +0100
From:   Patrick Bellasi <patrick.bellasi@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        Ingo Molnar <mingo@...hat.com>, 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>,
        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 v4 03/16] sched/core: uclamp: add CPU's clamp groups
 accounting

On 12-Sep 19:34, Peter Zijlstra wrote:
> On Tue, Aug 28, 2018 at 02:53:11PM +0100, Patrick Bellasi wrote:
> > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> > index 72df2dc779bc..513608ae4908 100644
> > --- a/kernel/sched/sched.h
> > +++ b/kernel/sched/sched.h
> > @@ -764,6 +764,50 @@ extern void rto_push_irq_work_func(struct irq_work *work);
> >  #endif
> >  #endif /* CONFIG_SMP */
> >  
> > +#ifdef CONFIG_UCLAMP_TASK
> > +/**
> > + * struct uclamp_group - Utilization clamp Group
> > + * @value: utilization clamp value for tasks on this clamp group
> > + * @tasks: number of RUNNABLE tasks on this clamp group
> > + *
> > + * Keep track of how many tasks are RUNNABLE for a given utilization
> > + * clamp value.
> > + */
> > +struct uclamp_group {
> > +	int value;
> > +	int tasks;
> > +};
> 
> We could use bit fields again to compress in 10:22 bits I suppose. 4M
> tasks is quite a lot to have runnable on a single CPU ;-)

If you say saw, it's ok with me... my Android phone can (yet) run so
many ;)

Cheers Patrick

-- 
#include <best/regards.h>

Patrick Bellasi