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

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Message-ID: <20080311183149.0f44e603@mjolnir.drzeus.cx>
Date:	Tue, 11 Mar 2008 18:31:49 +0100
From:	Pierre Ossman <drzeus-list@...eus.cx>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	linux-pm@...ts.linux-foundation.org,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>,
	Dave Jones <davej@...emonkey.org.uk>,
	Alan Stern <stern@...land.harvard.edu>,
	Adam Belay <abelay@...ell.com>,
	Lee Revell <rlrevell@...-job.com>, Pavel Machek <pavel@....cz>
Subject: Re: [linux-pm] [PATCH] cpuidle: avoid singing capacitors

On Tue, 11 Mar 2008 16:20:26 +0100
Pierre Ossman <drzeus-list@...eus.cx> wrote:

> On Tue, 11 Mar 2008 11:48:22 +0100
> Andi Kleen <andi@...stfloor.org> wrote:
> 
> > > I have now found a very hacky workaround that is slightly better than
> > > disabling C3 altogether; making C3 exclusive to one core at a time. It
> > > seems to kill the noise and the system now spends 50% in C3, instead of
> > > 0%.
> > 
> > I suspect it won't do much of C3 if only one core is idle this way.
> > Most likely you just disabled C3 this way in a way invisible to software.
> > 
> 
> What a letdown... I'll pull out the old watt meter again and see if I can confirm that.
> 

It seems that you are correct Andi. Power usage is in line with C3 completely disabled. Bummer :/

-- 
     -- 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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