Experiences Porting a Molecular Dynamics Code to GPUs on a Cray XK7

GPU computing has rapidly gained popularity as a way to achieve higher performance of many scientific applications. In this paper we report on the experience of porting a hybrid MPI+OpenMP molecular dynamics code to a GPU enabled CrayXK7 to make a hybrid MPI+GPU code. The target machine, Indiana University’s Big Red II, consists of a mix of nodes equipped with two 16-core Abu Dhabi X86-64 processors, and nodes equipped with one AMD Interlagos X8664 processor and one Nvidia Kepler K20 GPU board. The code, IUMD, is a Fortran program developed at Indiana University for modeling matter in compact stellar objects (white dwarf stars, neutron stars and supernovas). We compare experiences using CUDA and OpenACC. Keywords-Molecular Dynamics; CUDA; OpenACC;