Performance modeling and tuning of an unstructured mesh CFD application

  • Authors:

  • William D. Gropp;Dinesh K. Kaushik;David E. Keyes;Barry Smith

  • Affiliations:

  • Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL;Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL;Mathematics & Statistics Department, Old Dominion University, Norfolk, VA, ISCR, Lawrence Livermore National Laboratory, Livermore, CA and ICASE, NASA Langley Research Center, Hampton, VA;Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL

  • Venue:
  • Proceedings of the 2000 ACM/IEEE conference on Supercomputing
  • Year:
  • 2000

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Abstract

This paper describes performance tuning experiences with a three-dimensional unstructured grid Euler flow code from NASA, which we have reimplemented in the PETSc framework and ported to several large-scale machines, including the ASCI Red and Blue Pacific machines, the SGI Origin, the Cray T3E and Beowulf clusters. The code achieves a respectable level ofperformance for sparse problems, typical of scientific and engineering codes based on partial differential equations, and scales well up to thousands of processors. Since the gap between CPU speed and memory access rate is widening, the code is analyzed from a memory-centric perspective (in contrast to traditional flop-orientation) to understand its sequential and parallel performance. Performance tuning is approached on three fronts: data layouts to enhance locality of reference, algorithmic parameters and parallel programming model. This effort was guided partly by some simple performance models developed for the sparse matrix-vector product operation.