Breezed is a small daemon to control the speed of the fan,
   depending on the current temperature of the computer. I have tested
   it only on a Thinkpad X61s.

 * INSTALLATION

   You can install it simply by running as root

     ./install.sh

   and de-install it with

     ./remove.sh

   You must have a configuration file in /etc/breezed.conf. Only one
   is currently provided in the archive, and it corresponds to the
   settings _I_ picked for _my_ Lenovo X61s.

   I have no idea if these settings are safe on this laptop (I guess
   so, since I have been using them for a few months now and it works
   perfectly), and I suspect they are not safe for another laptop.

 * ALGORITHM

   Breezed scans the temperatures every 5s and sets the fan speed
   according to a series of thresholds.

   Unfortunately, if the fan speed is set directly according to these
   temperature thresholds, it creates oscillations: The fan goes up,
   temperature goes down, hence fan goes down, temperature goes up,
   etc.

   To mitigate such phenomenons, the daemon waits at least 30s after
   the last change before reducing the fan speed, and the actual
   thresholds to decrease the fan speed are two degrees below the
   provided thresholds, which are used when increasing the fan
   speed. This creates a stability area of two degrees, which seems to
   be enough. Please let me know if you have problem with the
   resulting overall behavior.

 * NOTES

   I wrote this daemon for my personal usage on a X61s, and using it
   may damage your hardware.

   On Thinkpads you have to allow the module thinkpad_acpi to set the
   fan speed, which is not allowed by default in Debian. To do so, you
   have to have a file /etc/modprobe.d/thinkpad_acpi.modprobe
   containing

   ---------------------------- snip snip -------------------------------
   options thinkpad_acpi fan_control=1
   ---------------------------- snip snip -------------------------------

--
Francois Fleuret (francois@fleuret.org)
December 2008