stress -- A tool to impose stress on a POSIX-compliant operating system.
http://weather.ou.edu/~apw/projects/stress/
Stress is a tool which imposes a configurable amount of CPU, memory, I/O,
or disk stress on a POSIX-compliant operating system. Stress is written
in highly-portable ANSI C, and uses the GNU Autotools to compile on a
great number of UNIX-like operating systems.
Stress is not a benchmark, it is rather a tool which puts the system
under a repeatable, defined amount of load so that a systems programmer
or system administrator can analyze the performance characteristics of
the system or specific components thereof.