Gyrokinetic toroidal simulations on leading multi- and manycore HPC systems

  • Authors:
  • Kamesh Madduri;Khaled Z. Ibrahim;Samuel Williams;Eun-Jin Im;Stephane Ethier;John Shalf;Leonid Oliker

  • Affiliations:
  • NERSC/CRD, Lawrence Berkeley National Laboratory, Berkeley;NERSC/CRD, Lawrence Berkeley National Laboratory, Berkeley;NERSC/CRD, Lawrence Berkeley National Laboratory, Berkeley;Kookmin University, Seoul, Korea;Princeton Plasma Physics Laboratory, Princeton;NERSC/CRD, Lawrence Berkeley National Laboratory, Berkeley;NERSC/CRD, Lawrence Berkeley National Laboratory, Berkeley

  • Venue:
  • Proceedings of 2011 International Conference for High Performance Computing, Networking, Storage and Analysis
  • Year:
  • 2011

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Abstract

The gyrokinetic Particle-in-Cell (PIC) method is a critical computational tool enabling petascale fusion simulation research. In this work, we present novel multi- and manycore-centric optimizations to enhance performance of GTC, a PIC-based production code for studying plasma microturbulence in tokamak devices. Our optimizations encompass all six GTC sub-routines and include multi-level particle and grid decompositions designed to improve multi-node parallel scaling, particle binning for improved load balance, GPU acceleration of key subroutines, and memory-centric optimizations to improve single-node scaling and reduce memory utilization. The new hybrid MPI-OpenMP and MPI-OpenMP-CUDA GTC versions achieve up to a 2x speedup over the production Fortran code on four parallel systems --- clusters based on the AMD Magny-Cours, Intel Nehalem-EP, IBM BlueGene/P, and NVIDIA Fermi architectures. Finally, strong scaling experiments provide insight into parallel scalability, memory utilization, and programmability trade-offs for large-scale gyrokinetic PIC simulations, while attaining a 1.6× speedup on 49,152 XE6 cores.