An optimized Lattice Boltzmann code for BlueGene/Q

Abstract

In this paper we describe an optimized implementation of a Lattice Boltzmann (LB) code on the BlueGene/Q system, the latest generation massively parallel system of the BlueGene family. We consider a state-of-art LB code, that accurately reproduces the thermo-hydrodynamics of a 2D-fluid obeying the equations of state of a perfect gas. The regular structure of LB algorithms offers several levels of algorithmic parallelism that can be matched by a massively parallel computer architecture. However the complex memory access patterns associated to our LB model make it not trivial to efficiently exploit all available parallelism. We describe our implementation strategies, based on previous experience made on clusters of many-core processors and GPUs, present results and analyze and compare performances. © 2014 Springer-Verlag.