Title: Acceleration of unstructured implicit low-order finite-element earthquake simulation using OpenACC on Pascal GPUs

Authors: Takuma Yamaguchi; Kohei Fujita; Tsuyoshi Ichimura; Muneo Hori; Lalith Maddegedara

Addresses: Department of Civil Engineering, Earthquake Research Institute, The University of Tokyo, Bunkyo, Tokyo, Japan ' Department of Civil Engineering, The University of Tokyo, Earthquake Research Institute, Bunkyo, Tokyo, Japan; Advanced Institute for Computational Science, RIKEN, Kobe, Hyogo, Japan ' Department of Civil Engineering, Earthquake Research Institute, The University of Tokyo, Bunkyo, Tokyo, Japan ' Department of Civil Engineering, Earthquake Research Institute, The University of Tokyo, Bunkyo, Tokyo, Japan ' Department of Civil Engineering, Earthquake Research Institute, The University of Tokyo, Bunkyo, Tokyo, Japan

Abstract: We accelerate CPU-based unstructured implicit low-order finite-element simulations by porting to a GPU-CPU heterogeneous compute environment using OpenACC. We modified performance-sensitive parts of the code, such as sparse matrix-vector multiplication and MPI communication, so that computations would be suitable for GPUs. Other parts of the earthquake simulation code are ported by directly inserting OpenACC directives into the CPU code. This porting approach enables high performance with relatively low development costs. When comparing eight K computer nodes and eight NVIDIA Pascal P100 GPUs, we achieve 20.8 times speedup for the 3 × 3 block Jacobi preconditioned conjugate gradient finite-element solver. We show the effectiveness of the proposed method through many-case crust-deformation simulations and a large-scale computation using finite element model with 109 degrees-of-freedom on a GPU cluster.

Keywords: OpenACC; GPU; finite-element analysis; MPI; element-by-element method; conjugate gradient method.

DOI: 10.1504/IJHPCN.2019.097044

International Journal of High Performance Computing and Networking, 2019 Vol.13 No.1, pp.3 - 18

Available online: 11 Dec 2018 *

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