Difference between revisions of "How to use cpufrequtils"
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| − | + | {{NOTE|See the [[How_to_make_use_of_Dynamic_Frequency_Scaling|Dynamic Frequency Scaling HOWTO]] on how to avoid using cpu frequency scaling daemons by using the kernel builtin ondemand governor.}} | |
| − | |||
| − | |||
| − | : cpufreq-info | + | ==What is it?== |
| − | + | cpufrequtils is used to control the CPU frequency scaling deamon (speedstep, throttling, ...). | |
| − | cpufrequtils | + | |
| + | This package mainly has 2 programs: | ||
| + | :{{path|/usr/bin/cpufreq-info}} | ||
| + | :{{path|/usr/bin/cpufreq-set}} | ||
| + | It's basically a user-friendly alternative to using the [[How_to_make_use_of_Dynamic_Frequency_Scaling#Using_the_Sys_Interface|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. | ||
| + | |||
| + | ===Installation=== | ||
| + | ====Ubuntu==== | ||
| + | To install it on [[Ubuntu]], install the package cpufrequtils from your package manager or a terminal: | ||
| + | user@host:~$ sudo aptitude install cpufrequtils | ||
| + | |||
| + | |||
| + | ==Using cpufrequtils== | ||
| + | |||
| + | ===cpufreq-info=== | ||
| + | Gives general CPU information: | ||
| + | user@host:~$ cpufreq-info | ||
| + | cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006 | ||
Report errors and bugs to linux@brodo.de, please. | Report errors and bugs to linux@brodo.de, please. | ||
analyzing CPU 0: | analyzing CPU 0: | ||
| − | driver: | + | driver: centrino |
CPUs which need to switch frequency at the same time: 0 | CPUs which need to switch frequency at the same time: 0 | ||
| − | hardware limits: | + | hardware limits: 798 MHz - 2.00 GHz |
| − | available frequency steps: | + | available frequency steps: 798 MHz, 1.06 GHz, 1.33 GHz, 1.60 GHz, 2.00 GHz |
| − | available cpufreq governors: userspace, performance | + | available cpufreq governors: userspace, ondemand, conservative, powersave, performance |
| − | current policy: frequency should be within | + | current policy: frequency should be within 798 MHz and 2.00 GHz. |
| − | The governor " | + | The governor "conservative" may decide which speed to use |
within this range. | within this range. | ||
| − | current CPU frequency is | + | current CPU frequency is 798 MHz. |
| + | |||
| + | ===cpufreq-set=== | ||
| + | Allows setting | ||
| + | -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. | ||
| + | |||
| + | ===Examples=== | ||
| + | {{NOTE|Use cpufreq-info to see which frequencies and governors are available for your CPU. Examples were made on a Z60m with Intel Pentium M 2.0Ghz.}} | ||
| + | {{NOTE|''sudo'' is used in these examples to grant root privileges.}} | ||
| + | |||
| + | 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 | ||
Latest revision as of 15:25, 2 May 2007
NOTE!
See the Dynamic Frequency Scaling HOWTO on how to avoid using cpu frequency scaling daemons by using the kernel builtin ondemand governor.
Contents
What is it?
cpufrequtils is used to control the CPU frequency scaling deamon (speedstep, throttling, ...).
This package mainly has 2 programs:
- /usr/bin/cpufreq-info
- /usr/bin/cpufreq-set
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.
Installation
Ubuntu
To install it on Ubuntu, install the package cpufrequtils from your package manager or a terminal:
user@host:~$ sudo aptitude install cpufrequtils
Using cpufrequtils
cpufreq-info
Gives general CPU information:
user@host:~$ cpufreq-info
cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006
Report errors and bugs to linux@brodo.de, 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.
cpufreq-set
Allows setting
-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.
Examples
NOTE!
Use cpufreq-info to see which frequencies and governors are available for your CPU. Examples were made on a Z60m with Intel Pentium M 2.0Ghz.
NOTE!
sudo is used in these examples to grant root privileges.
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
