Mac OS X and Speedstep

[crazybus]

Is it normal for OS X to not use processor frequency scaling? The Macbook Pro 13" I'm using doesn't seem to ever lower it's clockspeed, as reported by cpu-x, using the default power management kernel extension. By contrast, with VoodooPower, Speedstep seems to work as you would expect. I haven't been able to come across any definitive answer on this yet.

[derFunkenstein]

On your Energy Saver are you set to "longest battery life", "best performance" or something custom?

[SNM]

I'm pretty sure it should -- what profile do you have set in Energy Saver?

[crazybus]

There are no profiles in Energy Saver -- I'm on Snow Leopard and only have the integrated 9400M graphics.

[SNM]

Oh, right, Snow Leopard ditched it because it's supposed to be able to do dynamic throttling via SpeedStep. Hrm. I've never bothered to check it myself. Maybe VoodooPower is just more aggressive than the default and you have some user background applications doing stuff?

[crazybus]

Now I feel a little foolish. I installed Coolbook and it shows Speedstep working properly, dropping down to 1600MHz on AC power and 800MHz on battery. I could have sworn cpu-x shows actual frequency in real time but maybe I was wrong. I was messing around with tweaking speedstep profiles using VoodooPower before doing a clean reinstall of Snow Leopard several weeks ago. False alarm then it seems.

[derFunkenstein]

it's cool, apparently it's just not as advanced as CPU-z

[crazybus]

Turns out I was partly right. CPU-x does show processor frequency scaling when used in conjunction with voodoopower, just not the default power management kext . Actual clock speeds can be verified with MSR Tools (along with values reported by the on die thermal sensors).