ACPI performance profile

[Markus Schönhaber]

Marco Mandl wrote:
> This applet only shows me the current frequency which is always the
> maximum.
>
> I followed your proposal and placed
> /usr/bin/echo ondemand >
> /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor in rc.local.
>
> I did not change a thing. But I found the following in syslog:
> localhost powersaved: enter 'speedstep_centrino' into CPUFREQD_MODULE in
> /etc/powersave/cpufreq. localhost powersaved: Cannot load cpufreq governors
> - No cpufreq driver available

Then maybe first we should make sure that the basics are there. Does
/sys/devices/system/cpu/cpu0/cpufreq
even exist on your machine? This is what it looks like for me:
$ ls -l /sys/devices/system/cpu/cpu0/cpufreq
insgesamt 0
-r--r--r-- 1 root root 4096 2006-11-04 23:13 affected_cpus
-r-------- 1 root root 4096 2006-11-04 23:13 cpuinfo_cur_freq
-r--r--r-- 1 root root 4096 2006-11-04 23:10 cpuinfo_max_freq
-r--r--r-- 1 root root 4096 2006-11-04 23:13 cpuinfo_min_freq
drwxr-xr-x 2 root root    0 2006-11-04 23:13 ondemand
-r--r--r-- 1 root root 4096 2006-11-04 23:13 scaling_available_frequencies
-r--r--r-- 1 root root 4096 2006-11-04 23:13 scaling_available_governors
-r--r--r-- 1 root root 4096 2006-11-04 23:13 scaling_cur_freq
-r--r--r-- 1 root root 4096 2006-11-04 23:13 scaling_driver
-rw-r--r-- 1 root root    0 2006-11-04 23:13 scaling_governor
-rw-r--r-- 1 root root 4096 2006-11-04 23:11 scaling_max_freq
-rw-r--r-- 1 root root 4096 2006-11-04 23:13 scaling_min_freq
drwxr-xr-x 2 root root    0 2006-11-04 23:10 stats

Yours should look similar.

If it doesn't exist, then the appropriate module that handles frequency 
selection is propably not loaded. For me it is 'p4-clockmod'. Guessing from 
the message above, the right one for you could be 'speedstep-centrino'. So 
maybe
sudo modprobe speedstep-centrino
brings '/sys/devices/system/cpu/cpu0/cpufreq' into existence. You should then 
be able to select the desired governor by 'echo'ing it's name 
to 'scaling_governor' as in the line you added to 'rc.local'.
Of course, the modules implementing the governors you want to use have also to 
be loaded.

> I have powersaved installed. Do I need any of the other cpufreq packages
> installed, too?

I don't have powersaved installed but powernowd. But AFAICT you need neither 
to get frequency scaling to work in the first place.
If you select the 'userspace' governor you need some userspace program that 
tells the kernel which frequency to choose. That's where, for example, 
powernowd comes into play.

Regards
  mks