CPU-frequency-scaling is done by the kernel. Slackware comes with all requirements necessarry to use this feature.

The kernelmdule which provides cpu-frequency-scaling is for AMD powernow_k8, for Intel ???, Slackware comes with the cpufrequtils-package which helps us to configure the frequency-scaling in an appropriate manner.

Note that on a laptop the appropriate kernelmodule for cpu-frequency-scaling is loaded automatically. If you're computer is not a laptop you'll have to load the module via modprobe.

The cpu-frequency-scaling can be done automatically by a so called governor or manually. The governors available are “conservative”, “ondemand”, “userspace” and “performance”. When you build your own kernel, you can choose one of the governors or “userspace” which allows for configuring cpu-frequency in userspace.

Functions of the governors: the governor “performance” sets always the highest frequency available for the processor. “ondemand” switches dynamically between the available frequencies depending on the systemload. “conservative” is similar to “ondemand”, but tries to use always the lowest frequency possible. “powersave” sets the frequency to the lowest possible. When you configure your kernel for “userspace” you can configure the different governors in userspace (which is most convenient).

The cpufrequtils-package provides two commands, with cpufreq-info you can find out which governor is configured and also some other informations for example about the available frequencies for your processor. The cpufre-set command can be used in order to set the appropriate governor.