Section: System Deamons (1.4)
Updated: Mar 2010


breezed - Fan control daemon  


breezed [options]  


breezed is a daemon to adjust the fan speed according to the computer temperature. It should be started through the adequate script in /etc/rc?.d.

Every 5s, breezed gathers all integer values from the thermal files, and takes the max as the overall temperature T. It then computes the highest fan speed whose temperature threshold is lower than T. If that speed is above the current speed, the daemon changes the fan speed accordingly. Otherwise it computes the lowest fan speed whose temperature threshold is two degrees above T, and sets the fan speed one level below. This two degree gap avoids too many oscillations. Also, the daemon waits for at least 30s after any change of the fan speed before reducing it. The fan speed is set by writing "level <speed_name>" into the specified fan file. The speed name is the level itself if no alternative is provided with the temperature threshold.

Options can not be specified twice, neither on the command line nor in the configuration file.



-h | --help
display help and exits
-v | --version
display the version number and exits
-d | --debug
run in verbose mode
-cf | --configuration-file <file>
set the configuration file (default is /etc/breezed.conf)
-ncf | --no-configuration-file
prevent the reading of a configuration file
-tf | --thermal-file <file1>[,file2]...
set the files to spool for temperatures.
-ff | --fan-file <file>
set the file to control the fan speed.
-tt | --temperature-thresholds <temp1>[:<speed_name_1>][,temp2[:speed_name_2]]...
set the temperature thresholds.



The configuration file is a succession of lines, each starting with one of the three keywords thermal_files, fan_file or temperature_thresholds, followed by the same parameter values as for the command line arguments. The default configuration file is located at /etc/breezed.conf



If a configuration file exists, the standard way to start breezed is to run it without arguments.

Starting it with all the arguments on the commande line can be done for instance with

breezed --no-configuration-file \
        --thermal-files /proc/acpi/thermal_zone/THM0/temperature,/proc/acpi/thermal_zone/THM1/temperature \
        --fan-file /proc/acpi/ibm/fan \
        --temperature-thresholds 52,54,56,58,60,62,64,68:full-speed

which specifies that when the temperature raises above 52C, the fan
level should be 1, when the temperature raises above 54C it should be
2, etc. The maximum speed level 8 should be chosen for temperatures
above 68C, and its name is "full-speed" (since no other speed name is
provided, the other ones are the default level names, hence their
numerical value).

Due to the two degrees gap between the thresholds to increase and the
thresholds to decrease the temperature, it will for instance remains
at speed 1 until the temperature goes down to 50C.

Because it takes into account all the values found in the thermal
files, you can use as well /proc/acpi/thermal_zone/THM?/temperature or



Written by Francois Fleuret <>. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU GPL.



This document was created by using the manual pages.
Time: 22:25:40 GMT, February 09, 2016