Difference between revisions of "Fan control scripts"

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(Comprehensive <tt>bash</tt> script with fine control over fan speed: Linux 2.6.22 needs fan_control=1)
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Revision as of 19:25, 8 September 2007

This page provides several scripts for controlling the ThinkPad's system fan according the its thermal sensors (overriding the embedded controller), in order to reduce fan noise and decrease power consumption.

These scripts rely on undocumented hardware features and override nominal hardware behavior. They may thus cause arbitrary damage to your laptop or data. Watch your temperatures!

Variable speed control scripts

The following scripts sets the fan speed according to the system's thermal sensors. In addition, they include a hack for preventing the annoying fan pulsing that occurs on some systems. Note that the fan levels, thresholds and anti-pulsing hacks are system-specific, so you may need to adjust them.

Comprehensive bash script with fine control over fan speed

This script works with any recent Linux kernel (2.6.14 and higher). It requires the ibm-acpi module to be loaded with the experimental=1 module parameter (e.g., # modprobe ibm_acpi experimental=1).

In Linux 2.6.22 and higher you need to pass fan_control=1 to the module thinkpad_acpi (e.g., # modprobe thinkpad_acpi fan_control=1)

The code lets you define a temperature range for each thermal sensor. The script computes the fan level needed by each sensor based on the configured range, and then sets the the actual fan level to the slowest that will satisfy all sensors (plus some hysteresis to avoid fluctiations). It also includes a workaround for the pulsing noise problem. The scipt provides an (optional) daemon mode and logging to syslog. The method of controlling fan speed is documented here.

The system hard disk temperature is monitored as well, using the hard disk's internal sensor. This works only on certain Hitachi disks and requires kernel >= 2.6.19-rc1 or the ide driver, since it uses a non-standard method for reading the temperature without causing a head unload or spinup.

The code:

Current options:

Usage: ./tp-fancontrol [OPTION]...

Available options:
  -s N   Shift up the min temperature thresholds by N degrees
         (positive for quieter, negative for cooler).
         Max temperature thresholds are not affected.
  -S N   Shift up the max temperature thresholds by N degrees
         (positive for quieter, negative for cooler). DANGEROUS.
  -t     Test mode
  -q     Quiet mode
  -d     Daemon mode, go into background (implies -q)
  -l     Log to syslog
  -k     Kill already-running daemon
  -u     Tell already-running daemon that the system is being suspended
  -p     Pid file location for daemon mode
The list of temperature ranges used in this script is much more liberal than the rules used by the embedded controller firmware, and is derived mostly from anecdotal evidence, hunches and wishful thinking. It is also model-specific - see thermal sensors.

init script for the comprehensive script

This is optional. It assumes that the above tp-fancontrol script is saved at /usr/bin/tp-fancontrol.

Simple bash script with fine control over fan speed (requires kernel patch)

The following is a simpler patch (without extra features like daemon mode and logging). It requires the patch for controlling fan speed or a recent kernel (>=2.6.19).

tp-fancontrol-basic (download)

Fan enable/disable scripts

The following scripts were written before it was known how to control the fan speed, so they only toggle between fan disabled and default (noisy) fan behavior. In some models, they also do not monitor all available thermal sensors.

sh script example

fan-enable-basic (download)

sh script with more features

fan-enable-extended (download)

sh script with extra safety functionality

ibm_acpi usually works well. But to rely on it completely, this script provides some extra safety functionality:

  1. It catches various signals and turns the fan on before it quits.
  2. It turns off the fan under very strict conditions, leaving it on when unexpected errors occur.

fan-enable-safe (download)

Init scripts

Init script example

fan-enable.init (download)

Init script example for gentoo

Assume one of the above control scripts is /usr/sbin/ibm-fancontrold, for gentoo use the following init script in /etc/init.d/ibm-fancontrol. Copy the script to /etc/init.d/ibm-fancontrol, then do

# rc-update add ibm-fancontrol default

This will add the init script to the default runlevel.

ibm-fancontrol.init (download)

Init script example for rh/fedora

Assume one of the above control scripts is /sbin/tp-fancontrold, copy the script to /etc/init.d/tp-fancontrol, then do

# chkconfig --add tp-fancontrol

This will add the init script to the default runlevel.

tp-fancontrol-fc.init (download)

You'd have to install also "kernel-module-ibm-acpi" package.



fanctrld is a daemon (written in C) that controls the Thinkpad's fan. The basic approach is to monitor both temperature and fan speed. The fan is enabled when a certain temperature is exceeded, and disabled when the BIOS slows down the fan below a certain speed.

Ideas for improvement

  • Use the HDAPS sensor to automatically lower the temperature thresholds when the laptop is moving. Prolonged movement usually happens when the laptop is on the user's lap (see Problem with hot surfaces for implications), or when in a moving vehicle where fan noise is typically overshadowed by vehicle noise.
  • Use a PID controller feedback loop instead of simple thresholds.
  • Monitor the UltraBay disk temperature too.

See also

  • How to control fan speed
  • Shimodax's ThinkPad fan control tool for a Windows offers functionality similar to these scripts; see the forum discussion at thinkpads.com.
  • Yury Polyanskiy has a kernel patch for automatic fan control in kernelspace (only enable/disable based on maximum temperature).