3.2.3. Tuning CPUfreq Policy and Speed
Once you have chosen an appropriate CPUfreq governor, you can view CPU speed and policy information with the
cpupower frequency-info command and further tune the speed of each CPU with options for cpupower frequency-set.
For
cpupower frequency-info, the following options are available:
--freq— Shows the current speed of the CPU according to the CPUfreq core, in KHz.--hwfreq— Shows the current speed of the CPU according to the hardware, in KHz (only available as root).--driver— Shows what CPUfreq driver is used to set the frequency on this CPU.--governors— Shows the CPUfreq governors available in this kernel. If you wish to use a CPUfreq governor that is not listed in this file, refer to Procedure 3.2, “Enabling a CPUfreq Governor” in Section 3.2.2, “CPUfreq Setup” for instructions on how to do so.--affected-cpus— Lists CPUs that require frequency coordination software.--policy— Shows the range of the current CPUfreq policy, in KHz, and the currently active governor.--hwlimits— Lists available frequencies for the CPU, in KHz.
For
cpupower frequency-set, the following options are available:
Note
If you do not have the cpupowerutils package installed, CPUfreq settings can be viewed in the tunables found in
/sys/devices/system/cpu/[cpuid]/cpufreq/. Settings and values can be changed by writing to these tunables. For example, to set the minimum clock speed of cpu0 to 360 KHz, use:
echo 360000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq