High-performance external stencil computations using user-controllable I/O

The UPIO (User-controllable Parallel I/O) we proposed in [10] extends the abstraction of a linear file model into an n-dimensional file model and removes the limitations of the linear file model, allowing users to control the layout of data blocks across disks and aggregating disk bandwidth through UPIO's interfaces. This enables users to do plan I/Os, computations, communications, and data reuse effectively in many scientific and engineering applications. These applications can be characterized by the corresponding stencil and implemented using stencil algorithms. In this paper we show how well UPIO produces high-performance external stencil codes by designing I/O and communication-efficient external Laplace equation solver algorithms and exploring the effects of UPIO with the codes.