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From: Viresh Kumar <viresh.kumar@linaro.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	linaro-kernel@lists.linaro.org, linux-pm@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Vincent Guittot <vincent.guittot@linaro.org>
Subject: Re: [PATCH] cpufreq: schedutil: govern how frequently we change frequency with rate_limit
Date: Mon, 20 Feb 2017 15:28:03 +0530	[thread overview]
Message-ID: <20170220095803.GT21911@vireshk-i7> (raw)
In-Reply-To: <20170217124854.GD6500@twins.programming.kicks-ass.net>

On 17-02-17, 13:48, Peter Zijlstra wrote:
> On Fri, Feb 17, 2017 at 01:15:56PM +0100, Rafael J. Wysocki wrote:
> > On Thursday, February 16, 2017 01:36:05 PM Peter Zijlstra wrote:
> > > On Thu, Feb 16, 2017 at 03:42:10PM +0530, Viresh Kumar wrote:
> > > > But when I discussed this with Vincent, he suggested that it may not be required
> > > > at all as the scheduler (with the helped of "decayed") doesn't call into
> > > > schedutil too often, i.e. at least 1 ms. And if the CPUs are stable enough (i.e.
> > > > no interruptions to the running task), we wouldn't reevaluate before the next
> > > > tick.
> > > 
> > > There are still the attach/detach callers to cfs_rq_util_change() that
> > > kick in for fork/exit and migration.
> > > 
> > > But yes, barring those we shouldn't end up calling it at silly rates.
> > 
> > OK
> > 
> > Does this mean that running governor computations every time its callback
> > is invoked by the scheduler would be fine?
> 
> I'd say yes right up till the point someone reports a regression ;-)

@Rafael: Do you want me to send a V2 with the changes you suggested in
commit log?

-- 
viresh

  reply	other threads:[~2017-02-20  9:58 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-15 17:15 [PATCH] cpufreq: schedutil: govern how frequently we change frequency with rate_limit Viresh Kumar
2017-02-15 22:35 ` Rafael J. Wysocki
2017-02-15 22:52   ` Rafael J. Wysocki
2017-02-16  0:02     ` Rafael J. Wysocki
2017-02-16 10:12       ` Viresh Kumar
2017-02-16 12:36         ` Peter Zijlstra
2017-02-17 12:15           ` Rafael J. Wysocki
2017-02-17 12:48             ` Peter Zijlstra
2017-02-20  9:58               ` Viresh Kumar [this message]
2017-02-20 13:49                 ` Rafael J. Wysocki
2017-02-20 14:53                   ` Rafael J. Wysocki
2017-02-16  6:27   ` Viresh Kumar

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