Publications

MPI Sessions: Leveraging runtime infrastructure to increase scalability of applications at exascale

Holmes, Daniel; Mohror, Kathryn; Grant, Ryan E.; Skjellum, Anthony; Schulz, Martin; Bland, Wesley; Squyres, Jeffrey M.

MPI includes all processes in MPI COMM WORLD; this is untenable for reasons of scale, resiliency, and overhead. This paper offers a new approach, extending MPI with a new concept called Sessions, which makes two key contributions: a tighter integration with the underlying runtime system; and a scalable route to communication groups. This is a fundamental change in how we organise and address MPI processes that removes well-known scalability barriers by no longer requiring the global communicator MPI COMM - WORLD.