Linux kernel supports CPU frequency modulation. In supported processors, using
cpufreq to gain access to this feature gives the system administrator a variable level of control over the CPU's
clock rate. The kernel includes five governors by default:
Conservative, Ondemand, Performance, Powersave, and Userspace. The
Conservative and
Ondemand governors adjust the
clock rate depending on the CPU load, but each with different algorithms. The
Ondemand governor jumps to maximum frequency on CPU load and decreases the frequency step by step on CPU idle, whereas the
Conservative governor increases the frequency step by step on CPU load and jumps to lowest frequency on CPU idle. The
Performance,
Powersave and
Userspace governors set the
clock rate statically:
Performance to the highest available,
Powersave to the lowest available, and
Userspace to a frequency determined and controlled by the user.
