A Humble Programmer

I have an Intel Celeron-M based Acer TravelMate 3000. The Celeron-M does not come with the SpeedStep technology, so it does not support frequency-scaling natively. But I got frequency-scaling working with p4-clockmod. This is disabled in Ubuntu (up to Edgy) by default, because there’s a significant delay when changing frequency on-demand. The following comment can be found in /usr/share/powernowd/cpufreq-detect.sh:

# Disabled for now - the latency tends to be bad enough to make it
# fairly pointless.

But by enabling it and turning of on-demand scaling, you can manually decrease CPU frequency to reduce heat and power-consumption when your laptop is lightly loaded. There’s how:

You need powernowd which is included in a standard Ubuntu installation. To make sure:

sudo apt-get install powernowd

Override the default configuration to enable p4-clockmod:

sudo su
echo "FREQDRIVER=p4-clockmod" >/etc/default/powernowd

To let your non-root account change CPU frequency, set the setuid bit of cpufreq-selector, so that it runs as root:

sudo chmod +s /usr/bin/cpufreq-selector

Now add the CPU frequency scaling monitor to your GNOME panel, you should be able to change the frequency by click on the icon.