CPUFREQ driver is provided by Linux kernel for user to
control processor performance states (P-States) on the fly at
runtime. Most of the processor power management on Linux
system has been focused on changing the processor
frequency and/or voltage to manage processor power
consumption depending on the workloads. If choose the
proper frequency according to system load, this mechanism
saves power. Number of P-States is processor dependence.
The higher the number of P-States, the slower the processor
frequency is running, and generates lower power
consumption.