Parallel algorithms and architectures

Abstract

In this paper we consider some of the central issues involved in the design of parallel algorithms. We describe several efficient algorithms for idealised shared memory architectures and draw some conclusions as to what would be required to implement them on a realistic physical architecture, i.e. one with distributed memory. We also describe some systolic algorithms for matrix computations, sequence comparison and molecular modelling, and briefly discuss their implementation on arrays of transputers. In the final section we discuss the question of whether the current preoccupation with architectural details in parallel algorithm design is likely to persist. We briefly describe some techniques which show that a physically realistic general purpose parallel architecture based on distributed memory can be constructed which will execute any shared memory parallel algorithm with no significant overhead due to communication. We thus have the attractive prospect in the very near future of architectural independence in parallel algorithm design.