cpuspeed or not ?

[micha]

Thanks to Fedora Core 2 and cpuspeed, the automatic CPU frequency scaling works.

I use gnome-cpufreq-applet to monitor the current frequency of the CPU. I have Pentium M, and the frequency is always at its lowest level except when I run a CPU-consuming process. Well that's the expected behavior, and it works even if my laptop is not on the battery.

So I'm wondering about the effects of the continuous frequency changes on the CPU life. I imagine it shortens CPU life because each frequency change involves power change. This generates transitory electrical state that shorten electrical circuit life. In other word, when you start your computer, a big amount of the life of the electrical components is spent (like for a car), and that might be the same thing about CPU frequency scaling.

The feature is only needed when the laptop is on the battery. It didn't find how to set up a "rule" to activate cpuspeed only when the laptop is on the battery. If anyone has an idea about that...

[jrblevin]

cpuspeed --help

Here is my /etc/cpuspeed.conf:
VMAJOR=1
VMINOR=1
DRIVER="centrino"
OPTS="-a /proc/acpi/ac_adapter/ACAD/state -t /proc/acpi/thermal_zone/ATF0/temperature 75"

You could make an acpid script to send cpuspeed a SIGUSR1 or SIGUSR2 to change its behavior.

Check out 'man acpid' and then have a look at my event file and scripts at:
http://jrblevin.freeshell.org/linux/v505dx/ac_adapter.event
http://jrblevin.freeshell.org/linux/v505dx/ac_adapter.sh
You don't need everything, just the basic case statement and the cpuspeed lines.

[micha]

Perfect ! Thanks a lot. That was very educative about acpi events and cpuspeed.

Now I'm creating a little event to switch off my screen when I close the lid...

[jrblevin]

Awesome, glad it helped. I want to make a suspend script that runs when the lid closes...if I ever get software suspend working right... :)