PNNL

Abstract

The Cray XMT provides hardware support for parallel algorithms that would be communication- or memory-bound on other machines. Unfortunately, even if an algorithm meets these criteria, performance suffers if the algorithm is too numerically intensive. We present a lookup-based approach that achieves a significant performance advantage over explicit calculation. We describe an approach to balancing memory bandwidth against on-chip floating point capabilities, leading to further speedup. Finally, we provide table lookup algorithms for a number of common functions.