Subject: Re: High pitched noise from laptop: processor.c in linux 2.6
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Lee Revell <rlrevell@joe-job.com>
Cc: Pavel Machek <pavel@ucw.cz>, M <mru@mru.ath.cx>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Sul, 2004-10-17 at 02:24, Lee Revell wrote:
> > And heavily reduced accuracy on a lot of laptops where 1000Hz
> > is enough to make the clock slide every time the battery state is
> > queried or an SMM event triggers.
> Wouldn't such a laptop be horribly broken?  1ms is a LONG time to
> disable interrupts.  That's millions of CPU cycles...

Yes, and most laptops have this problem. They use SMM traps to talk to
the battery including huge delay loops and during those SMM traps no
interrupt code runs.

> > Getting the best of both worlds depends on the stuff discussed at OLS
> > being finished, then you can have 1Khz accurancy and battery life
> I was not there but I imagine this involves a way to get 1khz accuracy
> with a 100Hz timer interrupt rate?

Think about

	add_timeout(timer, when, precision_desired)


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