linux-kernel - Re: [PATCH 2/3] cpuidle,menu: use interactivity

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Date:	Wed, 4 Nov 2015 08:01:38 -0800
From:	Arjan van de Ven <arjan@...ux.intel.com>
To:	riel@...hat.com, linux-pm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, rafael.j.wysocki@...el.com,
	len.brown@...el.com, daniel.lezcano@...aro.org
Subject: Re: [PATCH 2/3] cpuidle,menu: use interactivity_req to disable
 polling

On 11/3/2015 2:34 PM, riel@...hat.com wrote:
> From: Rik van Riel <riel@...hat.com>
>
> The menu governor carefully figures out how much time we typically
> sleep for an estimated sleep interval, or whether there is a repeating
> pattern going on, and corrects that estimate for the CPU load.
>
> Then it proceeds to ignore that information when determining whether
> or not to consider polling. This is not a big deal on most x86 CPUs,
> which have very low C1 latencies, and the patch should not have any
> effect on those CPUs.
>
> However, certain CPUs (eg. Atom) have much higher C1 latencies, and
> it would be good to not waste performance and power on those CPUs if
> we are expecting a very low wakeup latency.
>
> Disable polling based on the estimated interactivity requirement, not
> on the time to the next timer interrupt.
>
good catch!

Acked-by: Arjan van de Ven <arjan@...ux.intel.com>

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