Analysing and Modelling the Performance of the HemeLB Lattice-Boltzmann Simulation Environment

We investigate the performance of the HemeLB lattice-Boltzmann simula-tor for cerebrovascular blood flow, aimed at providing timely and clinically relevant assistance to neurosurgeons. HemeLB is optimised for sparse geome-tries, supports interactive use, and scales well to 32,768 cores for problems with ∼81 million lattice sites. We obtain a maximum performance of 29.5 billion site updates per second, with only an 11 % slowdown for highly sparse problems (5 % fluid fraction). We present steering and visualisation perfor-mance measurements and provide a model which allows users to predict the performance, thereby determining how to run simulations with maximum accuracy within time constraints