Splitting TCP for MPI Applications Executed on Grids

Abstract

In this paper, we first study the interaction between MPI applications and TCP on grids. Then, we propose MPI5000, a transparent applicative layer between MPI and TCP, using proxies to improve the execution of MPI applications on grids. Proxies aim at splitting TCP connections in order to detect losses faster and avoid to return in a slowstart phase after an idle time. Finally, we evaluate our layer executing the NAS Parallel Benchmarks on Grid'5000, the French research grid. The results show that our architecture reduces the number of idle timeout and of long-distance retransmissions for BT, SP and LU benchmarks. Using MPI5000, these applications can decrease their execution time by 35%, 28%, and, 15% respectively. A comparison with MPICH-G2 performances shows that our layer can even outperform a grid enabled MPI implementation.