Reliability and Modelability Advantages of Distributed Switching for Reconfigurable 2D Processor Arrays

Processor arrays have been used, either as the main computation engine or as special-purpose adjuncts, for a variety of applications requiring very high performance. As the size of such an array increases, the possibility of processor malfunctions, leading to loss of computational capabilities, can no longer be ignored. While many switching architectures and reconfiguration algorithms have been proposed for building processor arrays, modeling of their reliability has been inadequately addressed. In this paper, I study differences between 2D processor arrays with centralized and distributed switching, pointing to advantages of the latter in terms of reliability, regularity, modularity, and VLSI realizability. As important side results, I formulate the notions of reliability inversion (a less reliable system prevailing over a more reliable one due to modeling uncertainties) and modelability (the property of a system that makes it possible to derive tight reliability bounds, thus making reliability inversion less likely).