From: Dominik Brodowski <linux@dominikbrodowski.de>
To: Ducrot Bruno <ducrot@poupinou.org>
Cc: acpi-devel@lists.sourceforge.net, cpufreq@www.linux.org.uk
Subject: Re: [PATCH 2.6] update passive cooling algorithm
Date: Mon, 12 Jan 2004 18:39:22 +0100 [thread overview]
Message-ID: <20040112173922.GA6154@dominikbrodowski.de> (raw)
In-Reply-To: <20040112154611.GH14031@poupinou.org>
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On Mon, Jan 12, 2004 at 04:46:11PM +0100, Ducrot Bruno wrote:
> On Sun, Jan 11, 2004 at 10:12:55PM +0100, Dominik Brodowski wrote:
> > [Len, could you test and verify this patch, and push it to Linus, please?]
> >
> > The current algorithm used by Linux ACPI for passive thermal management has
> > two shortcomings:
>
> ...
>
> > +/* If a passive cooling situation is detected, primarily CPUfreq is used, as it
> > + * offers (in most cases) voltage scaling in addition to frequency scaling, and
> > + * thus a cubic (instead of linear) reduction of energy. Also, we allow for
> > + * _any_ cpufreq driver and not only the acpi-cpufreq driver.
> > + */
>
> Just a stupid question:
>
> What is best if processor heat issues (apart turning on the fan)?
>
> Reducing voltage of the processor, but still allowing it to run execution
> at 100% (which is the case if the processor is heating), or reduce
> amount of time allowed for the processor to execute?
voltage scaling. It offers a much better (quadratic) saving than clock
modulation (linear saving). Doing both [and you need to do it, as the CPU
won't run with fewer volts at the same frequency] gives you cubic savings.
Dominik
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next prev parent reply other threads:[~2004-01-12 17:39 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-11 21:12 [PATCH 2.6] update passive cooling algorithm Dominik Brodowski
2004-01-12 15:46 ` Ducrot Bruno
2004-01-12 17:39 ` Dominik Brodowski [this message]
2004-01-12 19:11 ` Ducrot Bruno
2004-01-13 8:40 ` Dominik Brodowski
2004-01-15 12:18 ` [ACPI] " Pavel Machek
2004-01-15 13:42 ` Ducrot Bruno
2004-01-15 22:34 ` Pavel Machek
[not found] ` <20040115223425.GC18488-I/5MKhXcvmPrBKCeMvbIDA@public.gmane.org>
2004-01-16 1:14 ` Micha Feigin
2004-01-16 11:24 ` [ACPI] " Ducrot Bruno
2004-01-28 22:43 ` Len Brown
-- strict thread matches above, loose matches on Subject: below --
2004-01-13 9:20 Dominik Brodowski
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