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Process Arrival Pattern Aware Alltoall and Allgather on InfiniBand Clusters Ying Qian Ahmad Afsahi1
 

Summary: 1
Process Arrival Pattern Aware Alltoall and Allgather on InfiniBand Clusters
Ying Qian Ahmad Afsahi1
Department of Electrical and Computer Engineering
Queen's University, Kingston, ON, CANADA K7L 3N6
ying.qian@ece.queensu.ca ahmad.afsahi@queensu.ca
Abstract
Recent studies show that MPI processes in real applications could arrive at an MPI collective
operation at different times. This imbalanced process arrival pattern can significantly affect the
performance of the collective operation. MPI_Alltoall() and MPI_Allgather() are communication-
intensive collective operations that are used in many scientific applications. Therefore, their efficient
implementations under different process arrival patterns are critical to the performance of scientific
applications running on modern clusters. In this paper, we propose novel RDMA-based process arrival
pattern aware MPI_Alltoall() and MPI_Allgather() for different message sizes over InfiniBand clusters.
We also extend the algorithms to be shared memory aware for small to medium size messages under
process arrival patterns. The performance results indicate that the proposed algorithms outperform the
native MVAPICH implementations as well as other non-process arrival pattern aware algorithms when
processes arrive at different times. Specifically, the RDMA-based process arrival pattern aware
MPI_Alltoall() and MPI_Allgather() are 3.1 times faster than MVAPICH for 8KB messages. On average,
the applications studied in this paper (FT, RADIX, and N-BODY) achieve a speedup of 1.44 using the

  

Source: Afsahi, Ahmad - Department of Electrical and Computer Engineering, Queen's University (Kingston)

 

Collections: Computer Technologies and Information Sciences