I thought I would write a little howto on how to get cpu frequency scaling to work directly with the kernel modules. These modules are generally more efficient for performance computing and battery life.
kernel >= 2.6.9
Step 1: Enable BIOS Support
Enter your BIOS at boot and make sure Cool'n'Quiet (AMD) or SpeedStep (Intel) is enable for you CPU. Some BIOS may not have option at all. If that is the case it is probably enabled by default. Other BIOS may have the option but it is listed as another name altogether. If that is the case check your BIOS manual for more info.
Step 2: Remove Userspace Scaling Software
powernowd sudo apt-get remove powernowd cpudyn sudo apt-get remove cpudyn
Step 3: Install CPU Module
Identify your cpu type by runnig the command cat /proc/cpuinfo You can also Check the following links
AMD Sempron/Athlon/MP ( K7 ) Socket Types: A, Slot A sudo modprobe powernow-k7 AMD Duron/Sempron/Athlon/Opteron 64 ( K8 ) Socket Types: 754, 939, 940, S1 ( 638 ), AM2 ( 940 ), F ( 1207 ) sudo modprobe powernow-k8 Intel Core Duo sudo modprobe speedstep-centrino Intel Pentium M sudo modprobe speedstep-centrino Others (Unknown) I'm not entirely sure which cpus are supported using this module. If your cpu doesn't work with one of the above methods try this one. sudo modprobe acpi-cpufreq
Step 4: Scaling Modules
sudo modprobe cpufreq_conservative sudo modprobe cpufreq_ondemand sudo modprobe cpufreq_powersave sudo modprobe cpufreq_stats sudo modprobe cpufreq_userspace
Step 5: Testing/Configuration
Show Available Governors
You should see output similar to
powersave conservative ondemand performance
conservative Description: CPU frequency is scaled based on load in incremental steps up and down.
sudo -s echo conservative > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
Advanced Configuration Options cd /sys/devices/system/cpu/cpu0/cpufreq/conservative
ondemand Description: CPU frequency is scaled based on load.
sudo -s echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
Advanced Configuration Options cd /sys/devices/system/cpu/cpu0/cpufreq/ondemand
performance Description: CPU only runs at max frequency regardless of load. Configuration Dir: N/A
sudo -s echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
powersave Description: CPU only runs at min frequency regardless of load. Configuration Dir: N/A
sudo -s echo powersave > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
Step 6: Load Modules at Boot
Add the following lines to the end of /etc/modules
cpufreq_conservative cpufreq_ondemand cpufreq_powersave cpufreq_stats cpufreq_userspace [Module from Step 3]
Step 7: Configure Modules at Boot
This step needs to be done in order for the modules to retain your settings. Make sure you have sysfsutils installed sudo apt-get install sysfsutils Then add the following lines to /etc/sysfs.conf devices/system/cpu/cpu0/cpufreq/scaling_governor=ondemand Where ondemand can be changed to another governor type (i.e. conservative, powersave, etc.). You can also add other configuration options that are specific to the governor selected.
Useful Links http://ubuntu.wordpress.com/2005/11/04/enabling-cpu-frequency-scaling/ http://martin.ankerl.org/category/linux/ http://gentoo-wiki.com/HOWTO_Undervolt_a_Pentium_M_CPU http://wejp.k.vu/projects/howto_cnq_athlon_64_x2/