Last November, I found out that sysctl was reporting that my Powerbook was running at 2/3rd speed. After fiddling it with a while, I finally gave up because 1) the speed kept resetting, and 2) because Xbench didn’t report anything funky (similar CPU score either way).
Reading the ‘What is Mac OS X?’ writeup inspired me to do some Open Firmware digging and figure out what was going on. So, went about booting in, and connecting via telnet (very cool, see also telnet downloading) and got some perplexing numbers:
name PowerPC,G4
cpu-version 80010303
state running
clock-frequency 1fca0554
bus-frequency 07ef4594
config-bus-frequency 07e8fe70
timebase-frequency 01fbd165
l2cr 80000000
force-reduced-speed 00000001
min-clock-frequency 032d4b20
max-clock-frequency 33ad5ec0
processor-to-bus-ratio*200000008
rounded-clock-frequency 1fb5ad00
recalced-clock-frequency1fbd1650
According to the Open Firmware, the current clock-speed *is* running at 533MHz, however XBench CPU results are exactly in line with what’s expected (I get a score of ~104). Weird, no? (actually, the weirdest part is the force-reduced-speed, that shouldn’t be one, maybe I’ll muck w/ this over the weekend.