linux-kernel - Re: [PATCH v7 03/15] sched/core: uclamp: Add system default clamps

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Message-ID: <20190318131050.GQ6058@hirez.programming.kicks-ass.net>
Date:   Mon, 18 Mar 2019 14:10:50 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Patrick Bellasi <patrick.bellasi@....com>
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 v7 03/15] sched/core: uclamp: Add system default clamps

On Mon, Mar 18, 2019 at 12:18:04PM +0000, Patrick Bellasi wrote:
> On 13-Mar 21:18, Peter Zijlstra wrote:
> > On Fri, Feb 08, 2019 at 10:05:42AM +0000, Patrick Bellasi wrote:
> > > +static void uclamp_fork(struct task_struct *p)
> > > +{
> > > +	unsigned int clamp_id;
> > > +
> > > +	if (unlikely(!p->sched_class->uclamp_enabled))
> > > +		return;
> > > +
> > > +	for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id)
> > > +		p->uclamp[clamp_id].active = false;
> > > +}
> > 
> > Because in that case .active == false, and copy_process() will have done
> > thr right thing?
> 
> Don't really get what you mean here? :/

Why don't we have to set .active=false when
!sched_class->uclamp_enabled?