Performance modeling and tuning of an unstructured mesh CFD application

• Main Authors: Gropp, William D., Kaushik, Dinesh K., Keyes, David E., Smith, Barry
• Format: Conference Proceeding
• Language: English
• Subjects: Computer systems organization > Architectures; Computer systems organization > Dependable and fault-tolerant systems and networks; General and reference > Cross-computing tools and techniques > Performance; Mathematics of computing > Mathematical analysis > Differential equations > Partial differential equations; Networks > Network performance evaluation
• DOI: 10.5555/370049.370405

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 of performance 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.