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Date: Tue, 1 Mar 2016 14:26:47 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Steve Muckle <steve.muckle@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>, Ingo Molnar <mingo@redhat.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, Vincent Guittot <vincent.guittot@linaro.org>,
        Morten Rasmussen <morten.rasmussen@arm.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Juri Lelli <Juri.Lelli@arm.com>,
        Patrick Bellasi <patrick.bellasi@arm.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Ricky Liang <jcliang@chromium.org>
Subject: Re: [RFCv7 PATCH 03/10] sched: scheduler-driven cpu frequency
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On Fri, Feb 26, 2016 at 08:17:46PM -0800, Steve Muckle wrote:
> > But then it would only make a difference if cpufreq_update_util() was not
> > used at all (ie. no callbacks installed for any policies by anyone).  The
> > only reason why it may matter is that the total number of systems using
> > the performance governor is quite large AFAICS and they would benefit from
> > that.
> 
> I'd think that's a benefit worth preserving, but I guess that's Peter
> and Ingo's call.

Probably worth it, most of this is on rather fast paths.

See commit 1cde2930e154 ("sched/preempt: Add static_key() to
preempt_notifiers") for example.