Quicksilver: A Proxy App for the Monte Carlo Transport Code Mercury

Like many other code teams, the developers of the Mercury Monte Carlo Transport code at Lawrence Livermore National Laboratory are being forced by the arrival of GPUbased supercomputers to substantially refactor their application to obtain acceptable performance on new architectures. This paper describes how we have designed, developed, and used Quicksilver, a proxy application for Mercury, to assist in this process. We explain the goals and principles that informed Quicksilver’s design and describe the features of Mercury that are and are not represented by the proxy. We recount some experiences testing Quicksilver and changes made to improve its ability to represent Mercury. Finally we explore how we have used Quicksilver and QS lite, a proxy app for Quicksilver, as prototypes to test potential refactorings and provide performance results on GPU and CPU platforms.