Stress imposes a configurable Amount of Load on your Systemhttp://weather.ou.edu/~apw/projects/stress/
stress is a simple tool that imposes a configurable amount of CPU, memory, I/O, and disk stress on POSIX-compliant operating systems. It is written in portable ANSI C, and uses the GNU Autotools to compile on most UNIX-like operating systems.
stress is not a benchmark. It is a tool used by system administrators to evaluate how well their systems will scale, by kernel programmers to evaluate perceived performance characteristics, and by systems programmers to expose the classes of bugs which only or more frequently manifest themselves when the system is under heavy load.