HPSF Conference 2025

Although MPI and Kokkos have long been used together, there were no well-defined methods for integrating them effectively. The only approach is to point the underlying Kokkos View buffers to MPI functions.
This causes several major pain points: handling non-contiguous Views, asynchronous operations in both models, and how MPI interacts with Kokkos Profiling. Kokkos Comm is an experimental MPI interface for the Kokkos C++ Performance Portability Programming ecosystem that aims to address these concerns and improve the productivity of Kokkos users.

Currently, Kokkos Comm integrates point-to-point collectives, handling of non-contiguous Views, and Kokkos Tools Profiling. Kokkos Comm also aims to be a springboard for new and improved features that go beyond MPI and Kokkos, allowing Kokkos to work with MPI, stream-triggered MPIs, and other non-MPI communication libraries (e.g., NCCL and RCCL). This presentation will cover the Kokkos Comm API, conversion of existing code, best practices, how Kokkos Comm can help address common issues in Kokkos/MPI, and upcoming additions to Kokkos Comm, such as persistent communication and device-initiated communication.