A Comparison between the Earth Simulator and AlphaServer Systems Using Predictive Application Performance Models

This work gives a detailed analysis of the relative performance between the recently installed Earth Simulator and systems built using Alpha processors. The Earth simulator is based on the NEC SX-6 vector processing node interconnected using a single-stage cross-bar network, whereas the HP AlphaServer nodes use superscalar microprocessors and are interconnected using the Quadrics fat-tree network. The performance that can be achieved results from an interplay of system characteristics, application requirements and scalability behavior. Detailed performance models are used here to predict the performance of two codes representative of ASCI computations, namely SAGE and Sweep3D. The performance models encapsulate fully the behavior of these codes and have been previously validated on many large-scale systems. They do not require access to a full sized system but rather rely on characteristics of the system as well as knowledge of the achieved singleprocessor performance. One result of this analysis is in the determination of an equivalent-sized Alpha-based machine that would be required to obtain the same performance as the Earth Simulator.