Check out the Phoronix Test Suite which is one of the most widely used performance measuring tool, and runs on Linux, FreeBSD, Windows, Mac OS X, etc.
Here is a description from their website:
The Phoronix Test Suite is the most comprehensive testing and
benchmarking platform available that provides an extensible framework
for which new tests can be easily added. The software is designed to
effectively carry out both qualitative and quantitative benchmarks in
a clean, reproducible, and easy-to-use manner.
Originally developed for automated Linux testing, support to the
Phoronix Test Suite has since been added for OpenSolaris, Apple Mac OS
X, Microsoft Windows, and BSD operating systems. The Phoronix Test
Suite consists of a lightweight processing core (pts-core) with each
benchmark consisting of an XML-based profile and related resource
scripts. The process from the benchmark installation, to the actual
benchmarking, to the parsing of important hardware and software
components is heavily automated and completely repeatable, asking
users only for confirmation of actions.