Collective communication on architectures that support simultaneous communication over multiple links

Traditional collective communication algorithms are designed with the assumption that a node can communicate with only one other node at a time. On new parallel architectures such as the IBM Blue Gene/L, a node can communicate with multiple nodes simultaneously. We have redesigned and reimplemented many of the MPI collective communication algorithms to take advantage of this ability to send simultaneously, including broadcast, reduce(-to-one), scatter, gather, allgather, reduce-scatter, and allreduce. We show that these new algorithms have lower expected costs than the previously known lower bounds based on old models of parallel computation. Results are included comparing their performance to the default implementations in IBM’s MPI. Categories and Subject Descriptors D.m [Software]: Miscellaneous General Terms Algorithms, Performance

• Type: Conference
• Year: 2006
• Where: PPOPP
• Authors: Ernie Chan, Robert A. van de Geijn, William Gropp, Rajeev Thakur
• Keywords: Collective Communication Algorithms, Distributed And Parallel Computing, MPI Collective Communication, Node, PPOPP 2006