Modelling the performance of large-scale systems

Performance modelling can be used throughout the development, deployment and maintenance of system hardware and application software. In this work the authors illustrate three uses of performance modelling 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. They 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. The modelling approach is application centric. A detailed model is developed for each application of interest based on a static analysis of the code but parametrised in terms of its dynamic behaviour.