Re: [PATCH 2.6] update passive cooling algorithm

Ducrot Bruno
2004-01-12T19:11:22Z

On Mon, Jan 12, 2004 at 06:39:22PM +0100, Dominik Brodowski wrote:
> 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.

Yes I know. But does it offer more 'cooling'?

--
Ducrot Bruno

-- Which is worse: ignorance or apathy?
-- Don't know. Don't care.