More CPU Scaling Problems

Stefan Lesicnik stefan at
Sun May 17 06:30:53 UTC 2009

On Sun, May 17, 2009 at 2:08 AM, Evan <eapache at> wrote:

> 1. What does Ubuntu use to scale CPU frequencies? Does it use the kernel
> method, as described at [1], or something else?
> 2. Did the method change between Intrepid and Jaunty?
> I ask these two questions because in Intrepid it worked fine
> out-of-the-box, and in Jaunty it's been doing some really creepy things.
> I originally started looking at this because the ignore_nice_load default
> value (discussed previously) appeared to have changed. I wanted to change it
> back, so as per the instructions at [1] I added the proper lines to my
> /etc/rc.local file. The value was ignored, and I filed a bug regarding it at
> [2].
> I recently decided to change the default state of my cores from ondemand to
> powersave, and since I saw no easier way to do it, I added another few lines
> to rc.local. These also appeared to be ignored. Since I can change the
> governor manually using the same cmd I added to rc.local, and I know
> rc.local is being properly read, I knew something was fishy, so I did a few
> experiments.
> This is what I determined: every few minutes, something changes the
> governor on my CPU cores back to ondemand. I have a relatively vanilla
> install of Jaunty 64, and I know I haven't installed anything extra that
> should be touching my cpu governors (feel free to prove me wrong on this).
> Both the gnome monitor applet and /sys/devices have been used to change the
> governor, and both agree that it changes back. The ignore_nice_load value
> doesn't seem to change, but the fact that it's being ignored seems like it's
> probably related.
> Is something funny going on, or am I barking up the wrong tree?
> Evan
> [1]
> [2]
Hi Evan,

I am not sure (i looked at it briefly a while back), but I think its using
HAL.  Thats why  /usr/lib/hal/hald-addon-cpufreq runs as a process.
Therefore the corresponding stuff is probably in
/usr/share/hal/fdi/policy/10osvendor/10-cpufreq.fdi, and you can use the
hal-get-property and hal-set-property commands to query and set.

If you want to do other stuff, i think killing that hald cpufreq process
should let you then... (although there may be a safer saner way to do this)

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