Overview of the IBM Blue Gene/P project
IBM Journal of Research and Development
Architecture of the Component Collective Messaging Interface
International Journal of High Performance Computing Applications
The IBM Blue Gene/Q interconnection network and message unit
Proceedings of 2011 International Conference for High Performance Computing, Networking, Storage and Analysis
Composable, non-blocking collective operations on power7 IH
Proceedings of the 26th ACM international conference on Supercomputing
PAMI: A Parallel Active Message Interface for the Blue Gene/Q Supercomputer
IPDPS '12 Proceedings of the 2012 IEEE 26th International Parallel and Distributed Processing Symposium
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The IBM Blue Gene/Q supercomputer has a 5D torus network where each node is connected to ten bi-directional links. In this paper we present techniques to optimize the MPI_Allreduce collective operation by building ten different edge disjoint spanning trees on the ten torus links. We accelerate summing of network packets with local buffers by the use of Quad Processing SIMD unit in the BG/Q cores and executing the sums on multiple communication threads created by the PAMI libraries. The net gain we achieve is a peak throughput of 6.3 GB/sec for double precision floating point sum allreduce, that is a speedup of 3.75x over the collective network based algorithm in the product MPI stack on BG/Q.