linux-kernel - Re: [PATCH V2 1/3] x86,idle: Quickly notice prediction failure for repeat mode

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Message-ID: <50572CD1.700@redhat.com>
Date:	Mon, 17 Sep 2012 09:59:45 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Youquan Song <youquan.song@...el.com>
CC:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	arjan@...ux.intel.com, lenb@...nel.org,
	Youquan Song <youquan.song@...ux.intel.com>
Subject: Re: [PATCH V2 1/3] x86,idle: Quickly notice prediction failure for
 repeat mode

On 09/17/2012 09:53 PM, Youquan Song wrote:
> The prediction for future is difficult and when the cpuidle governor prediction
> fails and govenor possibly choose the shallower C-state than it should. How to
> quickly notice and find the failure becomes important for power saving.
>
> cpuidle menu governor has a method to predict the repeat pattern if there are 8
> C-states residency which are continuous and the same or very close, so it will
> predict the next C-states residency will keep same residency time.

Could I convince you to try out my variation on
detect_repeating_intervals? :)

http://people.redhat.com/riel/cstate/cstate-stddev-converge.patch

I suspect that small change might help your code adapt to changed
conditions even faster.

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