Performance Evaluation of a Hybrid Programming Model for RSDFT on T2K Open Supercomputer

Abstract

Non-uniform memory access (NUMA) systems, where each processor has its own memory, have been popular platform in high-end computing. While some early studies had reported that a flat-MPI programming model outperformed an OpenMP/MPI hybrid programming model on SMP clusters, the hybrid of a shared-memory, thread- based programming and a distributed-memory, message passing programming is considered to be a promising programming model on the multi-core multi-socket NUMA clusters. We explore the performance of the OpenMP/MPI hybrid programming model on a large scale multi-core multi-socket cluster called T2K Open Supercomputer to reveal the nature of the hybrid programming model on such clusters. We extend the Real-Space Density Functional Theory (RSDFT) code to the OpenMP/MPI hybrid version. We show and discuss the performance for several routines in RSDFT code which have different characteristics in operation and communication.