Experiments with a parallel external memory system

Abstract

The theory of bulk-synchronous parallel computing has produced a large number of attractive algorithms, which are provably optimal in some sense, but typically require that the aggregate random access memory (RAM) of the processors be sufficient to hold the entire data set of the parallel problem instance. In this work we investigate the performance of parallel algorithms for extremely large problem instances relative to the available RAM. We describe a system, Parallel External Memory System (PEMS), which allows existing parallel programs designed for a large number of processors without disks to be adapted easily to smaller, realistic numbers of processors, each with its own disk system. Our experiments with PEMS show that this approach is practical and promising and the run times scale predictable with the number of processors and with the problem size. © Springer-Verlag Berlin Heidelberg 2007.