On Using SCALEA for Performance Analysis of Distributed and Parallel Programs

In this paper we give an overview of SCALEA, which is a new performance analysis tool for OpenMP, MPI, HPF, and mixed parallel/distributed programs. SCALEA instruments, executes and measures programs and computes a variety of performance overheads based on a novel overhead classification. Source code and HWprofiling is combined in a single system which significantly extends the scope of possible overheads that can be measured and examined, ranging from HW-counters, such as the number of cache misses or floating point operations, to more complex performance metrics, such as control or loss of parallelism. Moreover, SCALEA uses a new representation of code regions, called the dynamic code region call graph, which enables detailed overhead analysis for arbitrary code regions. An instrumentation description file is used to relate performance information to code regions of the input program and to reduce instrumentation overhead. Several experiments with realistic codes that cover MPI, OpenMP, HPF, and mixed OpenMP/MPI codes demonstrate the usefulness of SCALEA.