linux-kernel - Re: [PATCH 5/5] cpufreq: schedutil: do not update rate limit ts when freq is unchanged

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Date:	Thu, 19 May 2016 17:40:56 -0700
From:	Steve Muckle <steve.muckle@...aro.org>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	Steve Muckle <steve.muckle@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Juri Lelli <Juri.Lelli@....com>,
	Patrick Bellasi <patrick.bellasi@....com>,
	Michael Turquette <mturquette@...libre.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Len Brown <lenb@...nel.org>
Subject: Re: [PATCH 5/5] cpufreq: schedutil: do not update rate limit ts when
 freq is unchanged

On Fri, May 20, 2016 at 02:37:17AM +0200, Rafael J. Wysocki wrote:
> Also I think that it would be good to avoid walking the frequency
> table twice in case we end up wanting to update the frequency after
> all.  With the [4/5] we'd do it once in get_next_freq() and then once
> more in cpufreq_driver_fast_switch(), for example, and walking the
> frequency table may be more expensive that doing the switch in the
> first place.

If a driver API is added to return the platform frequency associated
with a target frequency, what do you think about requiring the
fast_switch API to take a target-supported frequency?