Stepping Up

Computational simulation is an important research tool for modern scientists. There are a range of different scales of high performance computing (HPC) resources available to scientists, from laptop and desktop machines, to small institutional clusters, to national HPC resources, and the largest parallel computers in the world. This paper outlines the challenges that developers and users face moving from small scale computational resources to larger scale parallel machines. We present an overview of various research efforts to improve performance on large scale systems to enable users and developers to gain an understanding of the performance issues often encountered by simulation codes.