Modelling the performance of large-scale systems

Performance modeling can be used throughout the development, deployment, and maintenance of system hardware and application software. In this work we illustrate three uses of performance modeling on large-scale systems: the verification of performance during system installation, the comparison of two large-scale systems, and the prediction of performance on possible future architectures. We detail how a performance model gave an expectation of the performance of ASCI Q, a 20Tflop system recently installed at Los Alamos. A comparison between ASCI Q and the Earth Simulator is also detailed resulting in the sizing of an AlphaServer system that has the same performance as the Earth Simulator. Our modeling approach is application centric. A detailed model is developed for each application of interest based on a static analysis of the code but parameterized in terms of its dynamic behavior.