What is it?
cpulimit is a simple program that attempts to limit the cpu usage of a process (expressed in percentage, not in cpu time). This is useful to control batch jobs, when you don't want them to eat too much cpu. It does not act on the nice value or other scheduling priority stuff, but on the real cpu usage. Also, it is able to adapt itself to the overall system load, dynamically and quickly.
cpulimit should run on every Linux 2.2 or greater. It has been reported by several users that cpulimit works fine even on SMP hardware, but there is a little difference in the meaning of cpu usage (see below).
If you can modify the source code of cpulimit to make it run in a non Linux OS, please notify me, so I can publish your code. I think that the only non-portable code is iterating through the process list.
Download last stable version from here:
or get the latest source code from Subversion repository with this command:
tar zxf cpulimit-xxx.tar.gz
Executable file name is cpulimit. You may want to copy it in /usr/bin.
Examples of use
Limiting the process 'bigloop' by executable name to 40% CPU:
Limiting a process by PID to 55% CPU:cpulimit --exe bigloop --limit 40
cpulimit --exe /usr/local/bin/bigloop --limit 40
Notescpulimit --pid 2960 --limit 55
If you have just one processor you can limit the percentage from 0% to 100%, and this is fine. But if your machine has four processors percentage may vary from 0% to 400%, so setting the limit to 200% means to use no more than half of the available power.
cpulimit should run at least with the same user running the controlled process. But it is much better if you run cpulimit as root, in order to have a higher priority and a more precise control.
Now cpulimit does limit also the children of the specified process. The code is still experimental, so let me know how it is.