AMD Cool'N'Quiet under Linux

[^rooker]

How to activate the automatic CPU frequency adjustment feature "Cool'n'Quiet" under Linux: http://www.linuxforen.de/forums/showthread.php?t=165014


Here's a rough explanation in English:

You need a really new kernel (2.6.x) and your kernelconfig should look like this:

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[*] Power Management support
 CPU Frequency scaling  --->[*] CPU Frequency scaling                                                
 Default CPUFreq governor (performance)  --->                                         
 ---   'performance' governor                                                                
 <*>   'ondemand' cpufreq policy governor                                              
 <*>   CPU frequency table helpers                                                           
 ---   CPUFreq processor drivers                                                             
 <*> AMD Opteron/Athlon64 PowerNow!

Enable the cpufreq governor:

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echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

How to watch the frequency change:

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watch -n0.1 cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq

I haven't verified this, yet - but I'm planning to do so.