The idea of IMB is to provide a concise set of elementary MPI
benchmark kernels. With one executable, all of the supported
benchmarks, or a subset specified by the command line, can be run.
The rules, such as time measurement (including a repetitive call
of the kernels for better clock synchronization), message lengths,
selection of communicators to run a particular benchmark (inside
the group of all started processes) are program parameters.

WWW: http://www.intel.com/cd/software/products/asmo-na/eng/cluster/mpi/219848.htm