p4-clockmod and possible powernowd regression ?

[Matt Zimmerman]

On Wed, Mar 23, 2005 at 10:57:25AM +0100, Olivier Cortes wrote:

> One or two weeks ago, i installed a warty system on an ASUS P4P800S-X
> (Intel P4 2.8Ghz). I immediately dist-upgraded to hoary, it went
> smoothly (beside the fact that some gnome apps mess themselves with
> their preferences, like gnome-system-monitor with the displayed columns,
> but that's not related to the packaging system).
> 
> At this time my cpufreq applet showed a nice descent to 349Mhz when the
> machine was idle, and displayed correctly the variations of the clock
> modulations when there were some.
> 
> Last week, i dist-upgraded one more time to follow hoary, and
> cpufreq-applet couldn't detect the cupfreq mode of my P4 any more
> (Showing "--- ??"). I investigated the problem, in powernowd, and found
> the message at boot :
> 
> Your CPU "Intel Pentium4(R) 2.8Ghz" is known to _not_ support frequency
> scaling !
> 
> BUT, if i manually put p4-clockmod in /etc/modules (it is not loaded by
> hotplug), and tweak /usr/share/powernowd/cpufreq-detect.sh to exit 0 at
> first line (not to test at all), i get my cpufreq applet back :)
> And my CPU obviously supports frequency scaling !

The message is a bit misleading in this case, but withdrawing support for
scaling on these CPUs was an intentional change.  See:

https://bugzilla.ubuntu.com/show_bug.cgi?id=7259

This caused major performance problems for many users, and apparently
doesn't save significantly on power consumption.

-- 
 - mdz