Network offloaded hierarchical collectives using ConnectX-2's CORE-Direct capabilities

  • Authors:
  • Ishai Rabinovitz;Pavel Shamis;Richard L. Graham;Noam Bloch;Gilad Shainer

  • Affiliations:
  • Mellanox Technologies, Inc.;Mellanox Technologies, Inc.;Oak Ridge National Laboratory;Mellanox Technologies, Inc.;Mellanox Technologies, Inc

  • Venue:
  • EuroMPI'10 Proceedings of the 17th European MPI users' group meeting conference on Recent advances in the message passing interface
  • Year:
  • 2010

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Abstract

As the scale of High Performance Computing (HPC) systems continues to increase, demanding that we extract even more parallelism from applications, the need to move communication management away from the Central Processing Unit (CPU) becomes even greater. Moving this management to the network, frees up CPU cycles for computation, making it possible to overlap computation and communication. In this paper we continue to investigate how to best use the new CORE-Direct support added in the ConnectX-2 Host Channel Adapter (HCA) for creating high performance, asynchronous collective operations that are managed by the HCA. Specifically we consider the network topology, creating a two-level communication hierarchy, reducing the MPI Barrier completion time by 45%, from 26.59 microseconds, when not considering network topology, to 14.72 microseconds, with the CPU based collective barrier operation completing in 19.04 microseconds. The nonblocking barrier algorithm has similar performance, with about 50% of that time available for computation.