Express versus PVM: A performance

Due to the increasing popularity of networked clusters of workstations and the need for portability across various parallel and distributed platforms, a number of programming environments have been proposed to develop parallel programs. Express and PVM are two such commonly used environments that are available on most commercial parallel computers as well as a variety of clusters of workstations. Programs developed under Express are portable, that is, a program developed on one hardware platform can run on another platform without any significant modification (provided Express is available on both platforms). PVM provides a similar portability and is particularly suitable for heterogeneous systems. In this paper, we make an experimental performance comparison of Express and PVM. The comparison is done by evaluation of their performance through benchmarking on three platforms: an Intel iPSC/860 hypercube parallel computer, a cluster of SUN workstations connected by an Ethernet, and a cluster of HP workstations connected by an FDDI ring. The performance measures include the timings of various communication primitives coded with Express and PVM. The results of Express and PVM on the iPSC/860 are also compared with the equivalent implementations using the NX messagepassing library of the iPSC/860. To make a comparison from the applications point of view, we have also benchmarked a suite of various applications including three different versions of Gaussian elimination, and the N-body problem. The performance results also enable us to compare three different hardware platforms. While it is not the purpose of this study to make a qualitative judgement on Express and PVM, we highlight their usefulness and provide an overview of their programming styles and main features.