thermald(8) System Manager’s Manual thermald(8)
thermald – start Linux thermal daemon
thermald [ OPTIONS ]
thermald is a Linux daemon used to prevent the overheating of plat‐
forms. This daemon monitors temperature and applies compensation using
available cooling methods.
By default, it monitors CPU temperature using available CPU digital
temperature sensors and maintains CPU temperature under control, before
HW takes aggressive correction action.
Thermal daemon looks for thermal sensors and thermal cooling drivers in
the Linux thermal sysfs (/sys/class/thermal) and builds a list of sen‐
sors and cooling drivers. Each of the thermal sensors can optionally be
binded to a cooling drivers by the in kernel drivers. In this case the
Linux kernel thermal core can directly take actions based on the tem‐
perature trip points, for each sensor and associated cooling device.
For example a trip temperature X in a sensor can be associates a cool‐
ing driver Y. So when the sensor temperature = X, the cooling driver
“Y” is activated.
Thermal daemon allows to change this relationship or add new one via a
thermal configuration file (thermal-conf.xml). This file is automati‐
cally created and used, if the platform has ACPI thermal relationship
table. If not this needs to be manually configured.
When there is a sensor, which has no associate cooling device, via con‐
figuration file or thermal relationship table, then this sensor is
tested for relationship with CPU load dynamically up to maximum 3
times. If there is no relationship, then it is added to a black list of
unbinded sensors and not tried again.
Optionally thermal daemon can act as an exclusive thermal controller by
using thermal sysfs and acting as a user space governor. In this case
kernel thermal core is not active and decision is taken by thermal dae‐
Show help options.
Print thermald version and exit.
Don’t become a daemon: Default is daemon mode.
log severity: info level and up.
log severity: debug level and up: Max logging.
Poll interval in seconds: Poll for zone temperature changes. To
disable polling, set to zero. Polling can only be disabled, if
available temperature sensors can notify temperature change
Act as exclusive thermal controller. This will use user-space
governor for thermal sysfs and take over control.
8 May 2013 thermald(8)