Keep Cool

Stop processes when your computer gets hot

by Philippe Fremy


I am running a dual-CPU gentoo linux system and I have recentely discovered a big problem: in my attempts to reduce the sound of the CPU fans, I lost a lot of cooling power. Now, everytime I emerge a new software, my CPU temperatures raises to 60 and sometimes 70 degrees. The CPUs are still alive (thanks Intel) but the computer tends to freeze easily.

After some thinking, I developed the counter-weapon to this geeky problem: the keep cool script. The idea is quite simple: watch the temperature. If it gets too high, just sleep the responsible process and wait until things cool down.


Keep Cool is a small python script that watches the temperature of your system, and sleep processes taking too much CPU when this temperatures rises above a given limit. I wrote it to solve my problem and publish it here in the hope that it helps solve some of yours. However, there is no guarantee of anything.

How it works

The temperature is parsed from the output of lmsensors. You might have to customise that a bit to match the output of your system. I am okay to help if don't know any python coding.

The most CPU consuming process is read from the output of ps, which might also be different on your system given the wide number of ps implementation and option set.

The script has to run with enough privileges to send stop and continue signals to the process taking the CPU. In case of Gentoo emerging, I run it as root also it might probably be possible to achieve the same effect with just the portage user rights. If somebody has a better proposal, I am ready to accept it. It might be a good idea to rewrite it in C to avoid running python program as root but I am just too lazy.

When a process is stopped, keep cool waits until the temperature gets down again. It then restarts the processes one by one.

There is a bunch of variables at the beginning of the script, that you can customise to your needs: the highest allowed temperature, the low temperature after which processes are restarted, the delay between two temperature check.


KeepCool in action :

werewindle /home/philippe/python/keepcool # python
22:42:13 CPU are above max temperature :  53.1
process stopped:  15046 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2.3/cc1plus -
1 process currently stopped
22:42:58 Temperature is down again :  47.6 49.7
Restarting  15046 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2.3/cc1plus -
22:43:28 CPU are above max temperature :  53.1
process stopped:  16130 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2.3/cc1plus -
process stopped:  16265 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2.3/cc1 -fpre
2 process currently stopped
22:43:43 Temperature is down again :  46.7 49.6
Restarting  16130 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2.3/cc1plus -
22:43:48 Temperature is down again :  48.7 49.7
Restarting  16265 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2.3/cc1 -fpre

As you can see, the summer is really hot in France.


The script is available here.


You need lmsensors

Very simple:



Bugs, suggestions, patch, I am open to feedback: Mail me.

Last modification : $Date: 2005/07/02 16:19:31 $ - $Author: philippe $