linux-kernel - Re: [PATCH v2 2/2] sched/uclamp: Protect uclamp fast path code with static key

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Message-ID: <20200624122819.GG4781@hirez.programming.kicks-ass.net>
Date:   Wed, 24 Jun 2020 14:28:19 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Patrick Bellasi <patrick.bellasi@...bug.net>
Cc:     Qais Yousef <qais.yousef@....com>, Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Chris Redpath <chris.redpath@....com>,
        Lukasz Luba <lukasz.luba@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] sched/uclamp: Protect uclamp fast path code with
 static key

On Wed, Jun 24, 2020 at 09:34:02AM +0200, Patrick Bellasi wrote:
> > +static DEFINE_STATIC_KEY_TRUE(sched_uclamp_unused);
> 
> I would personally prefer a non negated semantic.

That's what I said earlier as well.


> > +	 */
> > +	if (static_branch_likely(&sched_uclamp_unused))
> > +		return;
> 
> Moreover, something like:
> 
>        if (static_key_false(&sched_uclamp_enabled))
>                 return;
> 
> is not just good enough?

static_key_true/false() are the deprecated API.