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From: Steve Muckle <steve.muckle@linaro.org>
Subject: Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable
Date: Thu, 17 Mar 2016 06:55:34 -0700
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To: Juri Lelli <Juri.Lelli@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Michael Turquette <mturquette@baylibre.com>, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, morten.rasmussen@arm.com, dietmar.eggemann@arm.com, vincent.guittot@linaro.org, Michael Turquette <mturquette+renesas@baylibre.com>, Patrick Bellasi <patrick.bellasi@arm.com>

On 03/17/2016 02:40 AM, Juri Lelli wrote:
>> Could the default schedtune value not serve as the out of the box margin?
>>
> I'm not sure I understand you here. For me schedtune should be disabled
> by default, so I'd say that it doesn't introduce any additional margin
> by default. But we still need a margin to make the governor work without
> schedtune in the mix.

Why not have schedtune be enabled always, and use it to add the margin?
It seems like it'd simplify things.

I haven't looked at the schedtune code at all so I don't know whether
this makes sense given its current implementation. But conceptually I
don't know why we'd need or want one margin in schedutil which will be
tunable, and then another mechanism for tuning as well.