cdown / zcfan

A zero-configuration fan daemon for ThinkPads.

zcfan |

Zero-configuration fan control daemon for ThinkPads.

Features

• Extremely small (~250 lines), simple, and easy to understand code
• Sensible out of the box, configuration is optional (see "usage" below)
• Strong focus on stopping the fan as soon as safe to do so, without inducing throttling
• Automatic temperature- and time-based hysteresis: no bouncing between fan levels
• Watchdog support
• Minimal resource usage
• No dependencies

Usage

zcfan has the following default fan states:

Config name	thinkpad_acpi fan level	Default trip temperature (C)
max_temp	full-speed (or 7 if unsupported)	90
med_temp	4	80
low_temp	1	70

If no trip temperature is reached, the fan will be turned off.

The fan will also only be reduced once the temperature is now at least 10C below the trip temperature for the current fan state. This can be tuned with the config parameter temp_hysteresis.

To override these defaults, you can place a file at /etc/zcfan.conf with updated trip temperatures in degrees celsius and/or fan levels. As an example:

max_temp 85
med_temp 70
low_temp 55
temp_hysteresis 20

max_level full-speed
med_level 4
low_level 1

Hysteresis

We will only reduce the fan level again once:

1. The temperature is now at least temp_hysteresis Celsius (default 10C) below the trip point, and
2. At least 3 seconds have elapsed since the initial trip.

This avoids unnecessary fluctuations in fan speed.

Comparison with thinkfan

I wrote zcfan because I found thinkfan's configuration and code complexity too much for my tastes. Use whichever suits your needs.

Compilation

Run make.

Installation

1. Compile zcfan or install from the AUR package
2. Load your thinkpad_acpi module with fan_control=1
   • At runtime: rmmod thinkpad_acpi && modprobe thinkpad_acpi fan_control=1
   • By default: echo options thinkpad_acpi fan_control=1 > /etc/modprobe.d/99-fancontrol.conf
3. Run zcfan as root (or use the zcfan systemd service provided)

Disclaimer

While the author uses this on their own machine, obviously there is no warranty whatsoever.