On Tuesday 18 September 2007 16:12:45 Simon Jude wrote:

Hi, I've got a Sony VAIO that I like to run Ubuntu on. When I run it off the mains the CPU stays pegged at 1.995GHz and the CPU fan sounds like a hoover. When running on the battery the CPU stays at a nice 786MHz (or whatever) and the fan is nice and quiet. Is there a way to switch the CPU speed to the lower speed when it is running on mains to protect my hearing?!

I've tried cpufreq-set etc without luck, although I may not have used them properly!

Any tips would be appreciated!

Try a couple of things:

# ls /sys/devices/system/cpu/cpu0/

If that directory exists, it has various files in it worth looking at. If it doesn't, try:

# modprobe cpufreq_userspace cpufreq_powersave cpufreq_ondemand cpufreq_conservative

Though these require the existence of a cpufreq driver for your CPU. My Intel Centrino-like chip uses:

# modprobe speedstep_centrino

(Note: I think some of this is becoming deprecated in recent kernels but it still kind of works.)

If you have all this funky stuff is your /sys filesystem, you should be able to chose a performance profile like this:

# echo -n "conservative"

/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

where "conservative" means, "only gradually increase the CPU speed as demands are made of it". "powersave" is another good one, it means, "leave my CPU speed as slow as possible; wtf would I need my CPU to go faster than 600 MHz for anyway?!" (roughly translated).

Also, if you're a featurefull desktop environment geek, the KDE power management applet allows you to chose performance profiles and alter them in response to various events.

Cheers, Richard

Simon Jude s.jude@uea.ac.uk wrote:

[...] Is there a way to switch the CPU speed to the lower speed when it is running on mains to protect my hearing?!

Are you running something like cpudyn or cpuspeed? My command line: cpudynd -d -i 1 -p 0.4 0.75 -minf 0.2 -t 120 -h /dev/hda

Also check http://tuxmobil.org/sony.html to see if your model is odd.

Hope that helps,