Scaling Performance Tool MPI Communicator Management

The Scalasca toolset has successfully demonstrated measurement and analysis scalability on the largest computer systems, however, applications have growing complexity and increasing demands on performance tools. One such application is the PFLOTRAN code for simulating multiphase subsurface flow and reactive transport. While PFLOTRAN itself and Scalasca runtime summarization both scale well, MPI communicator management becomes critical for trace collection with tens of thousands of processes. Re-design and re-engineering of key components of the Scalasca measurement system are presented which encompass the representation of communicators, communicator definition tracking and unification, and translation of ranks recorded in event traces.