2006/5/2, Warren Wilder <[EMAIL PROTECTED]>:
I have a question about scaling the frequency of the cpu clock cycle.

This isn't in the book, but I can't find much info on it otherwise.

It is/should be possible to set the cpu frequency governor in userspace.
This can be done with the cpufrequtils package from:
http://www.kernel.org/pub/linux/utils/kernel/cpufreq/cpufrequtils.html
together with the daemon from:
http://cpufreqd.sourceforge.net/

There are a few files which are read by these programs.
/sys/devices/system/cpu/cpu0/cpufreq/*

Of course, you should also compile your kernel with support for the
various frequency governors.

Now, about my question.
I have a Via SP13000 mini-itx system with a processor that at maximum
can reach 1.3GHz.
However, in this file (the maximum allowed frequency for a governor):
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
it reads 2 GHz.
The minimum allowed frequency in:
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq
reads 800 MHz.

The maximum value is obviously not correct for my system. I wonder
whether there is actually something wrong, or whether I should simply
use the cpufrequtils to set a maximum and minimum value by hand at every
boot. I also wonder what kind of value is sane as a minimum.

Right now, cpufreqd doesn't seem willing to let go of the "Performance
High" profile. This is probably because of the 2 Ghz value.

(I have read that the cpufrequency scaling support is superbly unstable
on this system, but I'd like to test that for myself.)


Greetings, Warren

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The 2Ghz limit is probably because the processor is not fully supported. You can try using the ondemand governor and see if you can set the values yourself.
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