cpu frequency on 6.0

Bruno Ducrot ducrot at poupinou.org
Mon Oct 17 07:19:28 PDT 2005


Answering to myself, somehow

On Mon, Oct 17, 2005 at 04:01:01PM +0200, Bruno Ducrot wrote:
> On Sun, Oct 16, 2005 at 06:54:12AM +0200, Zoran Kolic wrote:
> > Dear all!
> > I'd like to know, prior to
> > install upcoming 6.0, about
> > putting cpu into cooler mo-
> > de. On 5.4 and amd64 2800+ cpu
> > (754, 0.13) with "acpi_ppc",
> > it works fine and temperature
> > is just over 30. Could I do the
> > same with "device cpufreq" and
> > "powerd_enable"?
> 
> Yes.
> 
> > Also, is it possible to tune
> > celeron M processor (1400, says
> > it has "stepping=5") the same way?
> 
> It's possible to use p4tcc (integrated onto cpufreq.ko)
> I believe, but that will cool less the processor than other
> techniques (as for example est for the pentium-M).
> 

In fact the two answers I gave you are wrong.

powerd is used to give more power on demand, based upon cpu
utilization.  More performance is required, more the
frequency will be high.  As such, if there is a need to put
the processor to full speed, powerd by itself won't down the
frequency in order to cool the processor.  By now, Umemoto-san
have done some work, and I believe this has been commited
to 6.0.

Please search for "passive cooling" at current@ for more
informations.  This require though that the ACPI onto your
system support thermal zones.  There is no generic way to
do it for now unfortunately.

Of course, when the system is mostly idle, using powerd will
cool the processor, but this is only a side effect.  The same
statement apply also for acpi_ppc.

Cheers,

-- 
Bruno Ducrot

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


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