A Study of MPI Communication on a Next Generation Optical Interconnect

Abstract

For future HPC systems which embody tens of thousands of processors, it will be unfeasible to construct a fully-connected packet switching network with high bisection bandwidth due to cost and power consumption, etc. We propose a low cost hybrid network which exploits an EPS network whose bandwidths of upstream links are narrow and an OCS network. Moreover, we propose a forwarding based communication methodology where optical pathways are used as shortcuts of EPS upstream links for MPI applications. From results of simulation, we confirmed that combination of our network with our communication methodology achieved better performance than that of full bisection EPS only network with only small number of optical pathways in case of communication pattern which has locality. We also confirmed that in case of all-to-all communication, which does not have locality, the combination achieved almost the same performance as that of EPS only network whose upstream link bandwidth is twice larger than that of EPS network in our network.