CPU frequency scaling problem - laptop users, please check this

[A. Kromic]

I have a problem of CPU frequency scaling not working with kernels newer
than 2.6.32-24 (which I already discussed here a while ago). The bug is
reported here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/706089

The problem is, this problem seems to be ignored (nobody reacted at all
to fix this, something that perhaps deserves further comments); one of
the reasons could be that most people _have_no_idea_ what frequency
their CPU is running at! Therefore, probably there aren't enough reports
for anyone to investigate this...

So I'm asking people with Core2/Centrino Duo laptops if they could check
the frequency their CPU is running at. At the bug tracker, there is one
reply from an AMD Turion64 user to have the same problem, so perhaps
users of such machines could give it a try...

How to check it? One way is from the console, simply do:cat
/proc/cpuinfo. Within the results should be something like this:

model name    : Intel(R) Pentium(R) Dual  CPU  T2330  @ 1.60GHz
stepping    : 13
cpu MHz        : 800.000

The model name says my CPU normally works at 1.60 GHz, and below the
actual frequency is shown. For me, it normally should say "1600.000",
which it does with older kernels, but this happens with the newer ones.

The other way (perhaps easier) for Gnome users is to add the CPU
Frequency Scaling Monitor applet to a panel and see what frequency it
shows, the expected one or lower.

A notice, though... The default CPU governor lowers CPU frequency when
the CPU is unloaded. So, if you get a low frequency, most likely is that
everything works correct, you should change the frequency or governor
and recheck. Also, if you get a frequency which is not the lowest one
(but you should know what frequency is the lowest for your CPU), the
scaling should be ok.

On to changing the frequency. With Gnome applet it is simple, just click
on it and a menu will be shown where you can change the governor (you
should select "performance") or frequency (you should select any
frequency but the lowest, or simpy the highest one). If your CPU now
doesn't work at the lowest frequency from the menu, or works at the
exact one you chose, everything is fine.

In ccommandline you can try:

sudo cpufreq-set -g performance

(You should have /cpufrequtils/ package installed.) You can also set a
frequency:

sudo cpufreq-set -f 1600

(This is for my CPU, you should set yours to a supported frequency.)


However, if you find your CPU doesn't work at the expected frequency,
please see the above bugreport link and check "Affects Me" there. Thanks!

You may also be surprised at what you find by those tests ;)

-- 
A.Kromic
-
No trees were harmed in the sending of this message;
however, a large number of electrons were terribly inconvenienced.

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