Performance Measurements of the NERSC Cray Cascade System

Cray began delivery of their next generation XC30 supercomputer systems in late 2012. One of the first systems, “Edison,” was delivered to NERSC and in this paper we present preliminary performance results obtained on this machine. The primary new feature of the XC30 architecture is the Cray “Aries” interconnect that includes a 48-port high radix router with a dragonfly topology. To demonstrate the Aries’ substantial improvements in bandwidth, latency, message rate, and scalability, we present measurements of the basic performance characteristics of the system and examine the scalability of several network-centric “microbenchmarks.” Although some low-level microbenchmark results for Aries have been published previously (using prototype hardware), the unique contribution of this work consists of performance results for the NERSC Sustained System Performance (SSP) application benchmarks. The SSP benchmarks span a wide range of science domains, algorithms and implementation choices, and provide a more holistic performance metric. We examine the performance and scalability of these benchmarks on the XC30 and compare performance with other state-of-the-art HPC platforms. Edison nodes are composed of two eight-core Intel "Sandy Bridge" processors, which provide single-node performance to complement the networking improvements afforded by the Aries interconnect. Counting two hyperthreads per core, Edison has 32 hardware threads per node; thus, multi-threading is essential for obtaining optimal performance. We report the OpenMP, core-specialization and hyperthreading settings that maximize