Processor autonomy on SIMD architectures

Abstract

Flynn classified high speed (parallel) computers into four categories. Of these, the single instruction stream, multiple data stream (SIMD) processor array machines have become very popular in practical parallel processing. The commercially available processor array machines display important architectural variety, while belonging to SIMD category of machines. In this paper, we further categorize the SIMD class of machines on the basis of processor autonomy of the machines, which is the capability of the individual processing elements (PEs) to act autonomously in some significant way. For each autonomy class, we provide examples and illustrate some of its important algorithmic features. We also discuss how each type of autonomy can be simulated on machines without it. We study the addressing autonomous class of machines in greater detail by discussing three algorithms on machines with and without that type of autonomy. A discussion on how processor autonomy appears in algorithms in the literature and what impact they can have in the future machines also is provided.