Scaling Governors(Shell Script)

[Finalfantasykid]

I have been trying to get my laptop to change the scaling governors from Performance to OnDemand when it changes from AC to Battery. So far I have had no success(on older versions of Ubuntu I believe you could 8.04 and below, but I use 9.04).

So I figured I would make my own little shell script to do this. I didn't know shell scripting more than 3 hours ago, so if I made some blatant syntax mistakes/poor programming practices forgive me.


if on_ac_power
then
last=0
else
last=1
fi

while true; do
if on_ac_power
then
current=0
else
current=1
fi
if test $current -ne $last
then
if test 0 -eq $last
then
last=1
else
last=0
fi
if on_ac_power
then
cpufreq-selector -c 0 -g performance
cpufreq-selector -c 1 -g performance
else
cpufreq-selector -c 0 -g ondemand
cpufreq-selector -c 1 -g ondemand
fi
fi
sleep 5;
done
exit 0

This only works if you have done "sudo dpkg-reconfigure gnome-applets" and selected yes.

There is a problem with this code though. For some reason there is a massive delay between cpufreq-selector calls, like 10 seconds at least, which means that it the change doesn't happen immediatly. And if I put "cpufreq-selector -c 0 -g ondemand &" with the ampersand for example, it will sometimes spit out a ton of warnings saying something like the system bus is full.

Anyways. I'd like to use this as a startup application, that way it will properly scales the cpus depending on the situation. Any advice on this would be greatly appreciated.