[ltp] speedstep useful ?

[Richard Mittendorfer]

Also sprach Fr=E9d=E9ric BOITEUX <fboiteux@calistel.com> (Tue, 22 May 2007 =
08:16:34 +0200):
> 	Hello,

Hi,
=20
>   I've recently bought a Thinkpad X31=A0and installed a Debian Etch on
> it. It's my first laptop, and Debian Etch + ThinkWiki is a *very nice*
> way to have a full usable portable Linux computer !
>=20
>   One thing I=A0wonder is whether the Speedstep system is really useful

I'd say, it is: speedstep saves some power and won't run your CPU at
full speed all the time which keeps it cooler and may also lenghten
it's life.

> or not : The Debian Etch didn't installed the speedstep_centrino nor
> cpufreq_* modules, and the BIOS seems to put the processor in full speed

AFAIK, there is no good method for knowing what cpufreq module to
insert automaticaly. Add the right ones to /etc/modules after you know
which to use. Also, there is cpufrequtils. There you can configure what
governor to use and things like min/max speeds (if there are more..).

Don't know about your X31, so here you should should be able to find
more info: http://www.thinkwiki.org/wiki/Category:X31

> when on AC power and in low speed on batteries. Furthermore, I've tried

Yeah, IIRC I think it's best to disable this automatic switching in
BIOS, as it may confuse whatever you use later in OS.

> to install the modules and the gnome cpufreq applet, and this applet
> don't react/blocks when the speedstep module is loaded.

Set up cpufreq at the bootup. A gnomeapplet should be able to get it's
information later by checking the various files
in /sys/devices/system/cpu/... (that's also the place where you can
configure cpufreq by hand after inserting the right modules). See
<kernelsource>/Documentation/cpu-freq/ or $SEARCHENGINE for docs.

>   Is it a reason speedstep_centrino isn't loaded at boot time by Debian
> system ?
>   Does loading it can help in some way ? The only use I=A0see is to
> reduce cpu speed when idle on AC=A0power to reduce heat : correct ?
>=20
>   If you have any tips for a newbie, please tell me.
>=20
> 	With regards,

sl, ritch