linux-kernel - RE: [PATCH 1/1] intel_pstate: Increase hold-off time before busyness is scaled

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Date:	Fri, 19 Feb 2016 08:38:41 -0800
From:	"Doug Smythies" <dsmythies@...us.net>
To:	"'Stephane Gasparini'" <stephane.gasparini@...ux.intel.com>,
	"'Mel Gorman'" <mgorman@...hsingularity.net>
Cc:	"'Rafael Wysocki'" <rjw@...ysocki.net>,
	"'Ingo Molnar'" <mingo@...nel.org>,
	"'Peter Zijlstra'" <peterz@...radead.org>,
	"'Matt Fleming'" <matt@...eblueprint.co.uk>,
	"'Mike Galbraith'" <umgwanakikbuti@...il.com>,
	"'Linux-PM'" <linux-pm@...r.kernel.org>,
	"'LKML'" <linux-kernel@...r.kernel.org>,
	"'Srinivas Pandruvada'" <srinivas.pandruvada@...ux.intel.com>
Subject: RE: [PATCH 1/1] intel_pstate: Increase hold-off time before busyness is scaled

Hi Steph,

On 2016.02.19 03:12 Stephane Gasparini wrote:
>
> The issue you are reporting looks like one we improved on android by using 
> the average pstate instead of using the last requested pstate
>
> We know that this is improving the ffmpeg encoding performance when using the
> load algorithm.
>
> see patch attached
>
> This patch is only applied on get_target_pstate_use_cpu_load however you can give
> it a try on get_target_pstate_use_performance

Yes, that type of patch works on the load based approach.

However, I do not think it works on the performance based approach. Why not?
Well, and if I understand correctly, follow the math and you end up with:

scaled_busy = 100%

scaled_busy = (aperf * 100% / mperf) * (max_pstate / * ((aperf * max_pstate) / mperf))

... Doug