Modelling the Performance of the Gaussian Chemistry Code on x86 Architectures

Gaussian is a widely used scientific code with application areas in chemistry, biochemistry and material sciences. To operate efficiently on modern architectures Gaussian employs cache blocking in the generation and processing of the twoelectron integrals that are used by many of its electronic structure methods. This study uses hardware performance counters to characterise the cache and memory behavior of the integral generation code used byGaussian in Hartree-Fock calculations. A simple performance model is proposed that aims to predict overall performance as a function of total instruction and cache miss counts. The model is parameterised for three different x86 processors – the Intel Pentium M, the P4 and the AMD Opteron. Results suggest that the model is capable of predicting execution times to an accuracy of between 5 and 15%. Use of this model in developing a dynamic cache blocking scheme is also discussed.