PAPI aims to provide the tool designer and application engineer with a
consistent interface and methodology for use of the performance counter
hardware found in most major microprocessors.

PAPI enables software engineers to see, in near real time, the relation
between software performance and processor events.

WWW: http://code.google.com/p/papi-for-freebsd/
WWW: http://icl.cs.utk.edu/papi