Section: New Results

Multithreaded Communications

To program clusters of multicores, hybrid models mixing MPI+threads, and in particular MPI+OpenMP are gaining popularity. This imposes new requirements on communication libraries, such as the need for MPI_THREAD_MULTIPLE level of multi-threading support. Moreover, the high number of cores brings new opportunities to parallelize communication libraries, so as to have proper background progression of communication and communication/computation overlap.

We have proposed PIOMan [11] , a generic framework to be used by MPI implementations, that brings seamless asynchronous progression of communication by opportunistically using available cores. It uses system threads and thus is composable with any runtime system used for multithreading. Through various benchmarks, we demonstrated that our pioman-based MPI implementation exhibits very good properties regarding overlap, progression, and multithreading, and outperforms state-of-art MPI implementations.