Exploring the MPI tool information interface: features and capabilities

Abstract

The latest version of the MPI Standard, MPI 3.0, includes a new interface, the MPI Tools Information Interface (MPI_T), which provides tools with access to MPI internal performance and configuration information. In combination with the complementary and widely used profiling interface, PMPI, it gives tools access to a wide range of information in an MPI implementation independent way. In this paper, we focus on the new functionality offered by MPI_T and present two new tools to exploit this new interface by providing users with new insights about the execution behavior of their code: Varlist allows users to query and document the MPI environment and Gyan provides profiling information using internal MPI performance variables. Together, these tools provide users with new capabilities in a highly portable way that previously required in-depth knowledge of individual MPI implementations, and demonstrate the advantages of MPI_T. In our case studies, we demonstrate how MPI_T enables both MPI library and application developers to study the impact of an MPI library’s runtime settings and implementation specific behaviors on the performance of applications.