How to use cpufrequtils
What is it?
cpufrequtils is used to control the CPU frequency scaling deamon (speedstep, throttling, ...).
This package mainly has 2 programs:
It's basically a user-friendly alternative to using the Sys interface.
Frequency scaling allows you to set the CPU frequency on-the-fly or specify an automatic governor. By lowering the CPU frequency when your computer is idle, you can preserve a lot of battery power and keep the system cool.
By default most systems use the ondemand governor. For battery powered environments, the conservative and powersave governors are more favorable.
To install it on Ubuntu, install the package cpufrequtils from your package manager or a terminal:
user@host:~$ sudo aptitude install cpufrequtils
Gives general CPU information:
user@host:~$ cpufreq-info cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006 Report errors and bugs to firstname.lastname@example.org, please. analyzing CPU 0: driver: centrino CPUs which need to switch frequency at the same time: 0 hardware limits: 798 MHz - 2.00 GHz available frequency steps: 798 MHz, 1.06 GHz, 1.33 GHz, 1.60 GHz, 2.00 GHz available cpufreq governors: userspace, ondemand, conservative, powersave, performance current policy: frequency should be within 798 MHz and 2.00 GHz. The governor "conservative" may decide which speed to use within this range. current CPU frequency is 798 MHz.
-d minimum frequency, -u maximum frequency, -f specific frequency (userspace governor must be set first) and -g governor on a -c specific CPU.
cpufreq-set needs root privileges in order to work.
Activate the conservative governor to save a little extra power by letting the CPU stay longer at each frequency step before changing:
user@host:~$ sudo cpufreq-set -g conservative
Set the upper frequency limit to 1.6Ghz:
user@host:~$ sudo cpufreq-set -u 1.6Ghz
Manually set the frequency to a constant 800Mhz (userspace governor):
user@host:~$ sudo cpufreq-set -g userspace user@host:~$ sudo cpufreq-set -f 800Mhz