Implementation of two projection methods on a shared memory multiprocessor: DEC VAX 6240

Abstract

In this paper, we compare the relative performance of two iterative schemes, based on projection techniques, on a shared memory multiprocessor - VAX 6240. We consider the CG accelerated Block-SSOR method and the CG accelerated Symmetric-Kaczmarz method for the solution of large non-symmetric systems of linear equations. We show that the regular structure of many matrices can be exploited by the CG-accelerated Block-SSOR method to provide good speedup in a multiprocessing environment. However, the CG accelerated Symmetric-Kaczmarz method, while being a viable alternative on a scalar machine, is unable to benefit from multiprocessing.