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

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Date:	Mon, 3 Mar 2008 21:46:03 +0100
From:	Pavel Machek <pavel@....cz>
To:	Pierre Ossman <drzeus-list@...eus.cx>
Cc:	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	Adam Belay <abelay@...ell.com>,
	linux-pm@...ts.linux-foundation.org,
	LKML <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Lee Revell <rlrevell@...-job.com>
Subject: Re: [PATCH] cpuidle: avoid singing capacitors

Hi!

> I've been playing around with this for a bit, and the jiffies approach
> just had too many gotchas. So I tried using the information that was
> already present in the menu governor. This is what I came up with.
> 
> It solves the primary problem of getting rid of the noise. I've also
> tried some crude power measurements and I couldn't get any difference
> with and without the patch. Powertop also nicely shows that the CPU is
> still spending almost all of its time in C3. Therefore, I'm letting the
> effects of it be enabled by default.
> 
> So I'm taking the [RFC] off it. Please still test and see that it
> solves the issue on other machines, and the it does not cause any big
> power surges.
> 
> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> index 78d77c5..d9c43e3 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -16,6 +16,8 @@
>  
>  #define BREAK_FUZZ     4       /* 4 us */
>  
> +static unsigned int min_deep_sleep = 2000;
> +

Well, why not, but I believe we should default to old behaviour... not
all machines are cheaply-build.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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