An Investigation of Simultaneous Multithreading on HPCx

The use of Simultaneous Multithreading (SMT) on HPCx is investigated to determine if any performance improvement is obtainable for user applications. Various codes are benchmarked with and without the use of SMT. SMT is seen to boost the performance, at low and moderate processor counts, of the H2MOL application and the classical molecular dynamics codes NAMD, MDcask and DL POLY, with up to a factor of 1.4 improvement observed. No performance improvement is seen when using SMT with the materials science CASTEP code, the ScaLAPACK eigensolver routines or the STREAMS memory bandwidth benchmark.