CHARACTERIZATION BASED BOTTLENECK ANALYSIS OF PARALLEL SYSTEMS

Bottleneck analysis plays an important role in the early design of parallel computers and programs. In this paper a methodology for bottleneck analysis based on an instruction level characterisation technique is presented. The methodology is based on the assumption that a bottleneck is caused by the slowest component of a computing system, These components are: memory (internal, external), processor (CPU, FPU), communication and I/O. Three metrics were used to identify bottlenecks in the system components. These are the B-ratio, the communication-computation ratio and the memory-processing ratio. These ratios are dimensionless and indicate the presence of a bottleneck when their values exceed unity. The methodology is illustrated and validated using a communication intensive linear solver algorithm (Gauss-Jordan elimination) which was implemented on a mesh connected distributed memory parallel computer (128 T800 Parsytec SuperCluster)