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

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Message-ID: <20080311104822.GC18917@one.firstfloor.org>
Date:	Tue, 11 Mar 2008 11:48:22 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Pierre Ossman <drzeus-list@...eus.cx>
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>,
	Andi Kleen <andi@...stfloor.org>,
	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

> 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.

-Andi

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