Investigating the Usage of MPI at Argument-Granularity in HPC Codes

This study focuses on gaining insights into the usage of the Message-Passing Interface (MPI) in a large set of High-Performance Computing (HPC) codes by analyzing MPI function calls and their argument usage patterns. Previous work has focused on analyzing MPI feature usage by statically matching function calls. However, this approach does not reveal common argument-specific call patterns or cross-interactions between MPI functions. In particular, MPI exposes its internal data structures using handles, and users pass these handles to MPI constructor functions, e.g., to create custom communicators. Tracking the relevant MPI arguments of these constructors and cross-referencing them with other MPI calls in a target code can reveal common user interactions. These insights can be used to optimize, e.g., datatype construction at a library level or to extend MPI correctness debugging tools to verify correct construction of these data structures. To that end, we statically analyze codes to extract MPI function calls and their arguments, cross-reference them with other MPI calls, and provide statistics on common argument patterns and cross-use of MPI functions. We believe that these insights can guide further development within the MPI community to ultimately benefit users.