[mythtv-users] Cool'n'Quiet setup help

John Finlay finlay at moeraki.com
Mon Feb 9 01:03:51 UTC 2009


Allen Edwards wrote:
> I have an AMD 5400+ running Mythbuntu 8.10.  I would like to run 
> cool'n'quiet to cut the cpu temp and power.  I enabled it in the BIOS 
> and the results were unsatisfactory.  The program would stutter.  I 
> could see that the cpu was running at 1GHz during program mode and 
> that wasn't enough.
>
> What I want to do is have the CPU at a low clock frequency but when 
> there is basically any activity at all, have it go to 100% clock.  For 
> example, right now the CPU is at .6%.  It would be nice if the clock 
> was at a minimum.  But if the cpu goes above, say 2%?, I want the CPU 
> to go to max clock so it wont stutter.
>
> I see instructions on the net how to do this but they are 3 years old 
> and experience has thought me that following instructions like this 
> causes a half day work getting the system working again because the 
> instructions were for an older system.
>
> So, can anyone with a system like mine who has enabled cool'n'quiet 
> and understands what I am saying help me out?
>
> Allen
This uses the cpufreq module which uses the threshold (% cpu) in:

/sys/devices/system/cpu/cpu0/cpufreq/ondemand/up_threshold

As root you can change this e.g.:

echo -n 10 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/up_threshold

Other params in /sys/devices/system/cpu/cpu0/cpufreq can be changed as well:

scaling_max_freq
scaling_min_freq
ondemand/ignore_nice_load

If using Ubuntu you can set params on boot in the /etc/init.d/powernowd 
file. Add in the use_ondemand() function something like:

            if [ -f $x"cpufreq/ondemand/up_threshold" ]; then
                echo -n 20 > $x"cpufreq/ondemand/up_threshold"
            fi


If using Fedora the /etc/sysconfig/cpuspeed file allows you to tweak things.

John


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