powernowd vs. ondemand governor

Scott James Remnant scott at canonical.com
Wed Feb 18 13:42:06 GMT 2009

On Mon, 2009-02-16 at 14:58 +0000, Matt Zimmerman wrote:

> We currently ship powernowd in the desktop seed, its main purpose being to
> load cpufreq modules set up the kernel's CPU frequency scaling governor.  If
> (and only if) that fails, it starts up powernowd instead.  I'm not sure on
> which platforms that's still needed, if any.
> Is this still an appropriate default?  Aren't the necessary modules loaded
> automatically now?  Would it be a better idea to set the default to ondemand
> in the kernel and drop powernowd altogether?
Some investigation has shown that the shell script that tries to pick
the right scaling _driver_ isn't even working currently.  I had to
manually modprobe acpi-cpufreq.

You can check this with:

  cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_{driver,governor}

(if you get ENOENT, you have no scaling driver loaded, try modprobe

The scaling governors are all built into the kernel, but the default is
set to performance.

I've done some kernel patches to correct this, and Tim has applied them.

Scott James Remnant
scott at canonical.com
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