Abstract. SKaMPI is a benchmark for MPI implementations. Its purpose is the detailed analysis of the runtime of individual MPI operations and comparison of these for di erent implementations of MPI. SKaMPI can be con gured and tuned in many ways: operations, measurementprecision, communication modes, packet sizes, number of processors used etc. The technically most interesting feature of SKaMPI are measurement mechanisms which combine accuracy, e ciency and robustness. Postprocessors support graphical presentation and comparisons of di erent sets of results which are collected in a public web-site. We describe the SKaMPI design and implementation and illustrate its main aspects with actual measurements. 1 The Role of Benchmarking in Parallel Programming The primary purpose of parallel (as opposed to sequential) programming is achieving high processing speed. There are two basic approaches to parallel programming. The high-level approach tries to maintain ease of programming as much as ...