linux-kernel - Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler utilization data

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Date:	Thu, 3 Mar 2016 17:47:51 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
Cc:	Vincent Guittot <vincent.guittot@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Juri Lelli <juri.lelli@....com>,
	Steve Muckle <steve.muckle@...aro.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Michael Turquette <mturquette@...libre.com>
Subject: Re: [PATCH 6/6] cpufreq: schedutil: New governor based on scheduler
 utilization data

On Thu, Mar 03, 2016 at 05:37:35PM +0100, Peter Zijlstra wrote:
> On Thu, Mar 03, 2016 at 05:24:32PM +0100, Rafael J. Wysocki wrote:
> > >> f = a * x + b

> > If not, then I think it's reasonable to map the middle of the
> > available frequency range to x = 0.5 and then we have b = 0 and a =
> > (max_freq + min_freq) / 2.
> 
> So I really think that approach falls apart on the low util bits, you
> effectively always run above min speed, even if min is already vstly
> over provisioned.

Ah nevermind, I cannot read. Yes that is worth trying I suppose. But the
b=0,a=1 thing seems more natural still.