CPU Frequency scaling

modulename: cpufreq.ko

configname: CONFIG_CPU_FREQ

Linux Kernel Configuration
└─>Power management and ACPI options
└─>CPU Frequency scaling
└─>CPU Frequency scaling
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
CPU Frequency scaling allows you to change the clock speed of
CPUs on the fly. This is a nice method to save power, because
the lower the CPU clock speed, the less power the CPU consumes.

Note that this driver doesn't automatically change the CPU
clock speed, you need to either enable a dynamic cpufreq governor
(see below) after boot, or use a userspace tool.

For details, take a look at

If in doubt, say N.

source code: