Apple powerpc cpu frequency scaling fix for 11.1

Due to my ppc G5 iMac’s hardware, cpufreq always stays at the performance frequency of 1.8ghz, and no amount of cpufreq-util manipulation could get it to accept ondemand or even conservative. (the console always reports that there was too much latency in the switch, so it defaults to performance no matter what.) I could manually change it down to powersave at 900mhz, but I wanted automatic scaling.

The fix was to use CPUDYN. Unfortunately, I couldn’t find it in the repos. Cpudyn is one of my favorites on other ppc distros too. I think this latency issue may affect more models than just mine, so it could be a great help for hot running ppc apple notebooks too.

All I had to do was install make and gcc from the repos to enable compilation.

I grabbed cpudyn-1.0.1.tgz from the project site:

cpudyn Project page

Untarred it with

tar -zxvf cpudyn-1.0.1.tgz

changed into the cpudyn directory, and su to root. Now I just compiled and installed it

make

then

make install

To make it active upon startup, I added the following line to /etc/init.d/boot.local

/etc/init.d/cpudyn start

Bingo! Now when I check the freq with /proc/cpuinfo, I see it idling at 900mhz, and with a load shoots up to 1.8ghz.

This was almost a deal-breaker for me, as powersaving saves me 10 watts as measured at the ac outlet, not to mention keeping my system cooler for the most part.

I’m sure there is a better way to do this, but I’m pretty chuffed with my late-night compiling session. :slight_smile: