Correlating Workload Characteristics to Performance Metrics for theCray X-MP/Y-MP

Workload characterization is essential for performance evaluation studies. For multiprocessor supercomputers, this characterization usually consists of program measurements from uniprocessor execution (e.g., average vector length, percentage vectorization, etc.). There is no consistent, quantitative correlation between such characteristics and performance metrics across different programs. We present a methodology for defining and measuring characterization parameters for both single and multi-processor executions. Using several production codes, we show for the Cray X-MP/Y-MP that these characterization parameters correlate consistently to observed performance metrics across different programs. Moreover, the correlation allows the identification of bottlenecks in system architecture that limit performance. Presentation slides from the Fourth SIAM Conference on Parallel Processing for Scientific Computing, December, 1989

Performance of Some CFD Codes on the Alliant FX/8

Three CFD codes are ported to the Alliant FX/8. The first solves the 3-D unsteady Euler equations using an explicit finite-volume Runge-Kutta time stepping method. The second solves the same problem using the Beam and Worming implicit method. The third is ARC2D from NASA Ames which solves the unsteady 2-D Navier-Stockes equations using an implicit method. Extensive observations and results on the performance of these codes on the FX/8 are presented. Careful interaction with parallelizing compiler improves the performance some. Better results are obtained by simple recoding of different segments in the programs