linux-kernel - Re: [linux-pm] [PATCH] cpuidle: avoid singing capacitors

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Message-ID: <20080304183032.17084e39@mjolnir.drzeus.cx>
Date:	Tue, 4 Mar 2008 18:30:32 +0100
From:	Pierre Ossman <drzeus-list@...eus.cx>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>,
	Dave Jones <davej@...emonkey.org.uk>,
	Andi Kleen <andi@...stfloor.org>,
	Alan Stern <stern@...land.harvard.edu>,
	LKML <linux-kernel@...r.kernel.org>,
	Adam Belay <abelay@...ell.com>,
	Lee Revell <rlrevell@...-job.com>,
	linux-pm@...ts.linux-foundation.org, Pavel Machek <pavel@....cz>
Subject: Re: [linux-pm] [PATCH] cpuidle: avoid singing capacitors

On Tue, 4 Mar 2008 18:29:18 +0100
Andi Kleen <andi@...stfloor.org> wrote:

> > So for now, I'm back to thinking that measuring the interval between deep sleeps is the better approach. I could use some ideas for a good clock source though. I haven't dug much deeper than jiffies when it comes to kernel timekeeping.
> 
> jiffies should work, you just need to make sure you measure them at the
> right place. In particular there is some code in dyntick that catches
> up on jiffies after the deep sleep when the normal timer handler didn't run
> and jiffies are only usable again after that code executed.
> 

And how can I tell if this handler has run? Not that it really matters I guess, as I don't think running it from the cpuidle governor is very sane.

-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org
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