Targeting GPUs with OpenMP directives on Summit: A simple and effective Fortran experience

Budiardja, Reuben D.; Cardall, Christian Y.

doi:10.1016/j.parco.2019.102544

Title: Targeting GPUs with OpenMP directives on Summit: A simple and effective Fortran experience

Journal Article · 20 August 2019 · Parallel Computing

DOI: https://doi.org/10.1016/j.parco.2019.102544 · OSTI ID:1569391

Budiardja, Reuben D. ^[1];

^[2]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Sciences; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Physics Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy

We use OpenMP to target hardware accelerators (GPUs) on Summit, a newly deployed supercomputer at the Oak Ridge Leadership Computing Facility (OLCF), demonstrating simplified access to GPU devices for users of our astrophysics code GenASiS and useful speedup on a sample fluid dynamics problem. We modify our workhorse class for data storage to include members and methods that significantly streamline the persistent allocation of and association to GPU memory. Users offload computational kernels with OpenMP target directives that are rather similar to constructs already familiar from multi-core parallelization. In this initial example we ask, “With a given number of Summit nodes, how fast can we compute with and without GPUs?”, and find total wall time speedups of ~ 12X. We also find reasonable weak scaling up to 8000 GPUs (1334 Summit nodes). We make available the source code from this work at https://github.com/GenASiS/GenASiS_Basics.

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Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR); USDOE

Grant/Contract Number:: AC05-00OR22725

OSTI ID:: 1569391

Alternate ID(s):: OSTI ID: 1776465

Journal Information:: Parallel Computing, Vol. 88, Issue C; ISSN 0167-8191

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 7 works

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References (10)

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Generation of Magnetic Fields by the Stationary Accretion Shock Instability Endeve, Eirik; Cardall, Christian Y.; Budiardja, Reuben D. The Astrophysical Journal, Vol. 713, Issue 2 https://doi.org/10.1088/0004-637X/713/2/1219	journal	April 2010
Turbulent Magnetic Field Amplification from Spiral sasi Modes: Implications for Core-Collapse Supernovae and Proto-Neutron star Magnetization Endeve, Eirik; Cardall, Christian Y.; Budiardja, Reuben D. The Astrophysical Journal, Vol. 751, Issue 1 https://doi.org/10.1088/0004-637X/751/1/26	journal	May 2012
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Stochasticity and Efficiency in Simplified Models of Core-Collapse Supernova Explosions Cardall, Christian Y.; Budiardja, Reuben D. The Astrophysical Journal, Vol. 813, Issue 1 https://doi.org/10.1088/2041-8205/813/1/L6	journal	October 2015
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GenASiS Basics: Object-oriented utilitarian functionality for large-scale physics simulations Cardall, Christian Y.; Budiardja, Reuben D. Computer Physics Communications, Vol. 196 https://doi.org/10.1016/j.cpc.2015.06.001	journal	November 2015
Turbulent Magnetic Field Amplification from Spiral SASI Modes: Implications for Core-Collapse Supernovae and Proto-Neutron Star Magnetization Endeve, Eirik; Cardall, Christian Y.; Budiardja, Reuben D. arXiv https://doi.org/10.48550/arxiv.1203.3108	text	January 2012