This tutorial shows how you can limit the CPU usage of a process with the tool cpulimit on Debian/Ubuntu. 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.