COOPERATIVE DIAGNOSIS AND ROUTING IN FAULT-TOLERANT MULTIPROCESSOR SYSTEMS

In this note, we consider the problem of fault-tolerant routing in multiprocessor systems when incomplete, or partial, diagnostic information is available. We first define a new type of partial diagnosis, known as k-reachability diagnosis. The overhead for k-reachability diagnosis increases with k, which specifies the radius of diagnostic information maintained by each node. We then present a routing algorithm, known as Algorithm Partial Route, that makes use of k-reachability diagnostic information and allows a trade-off between the amount of diagnostic information and the quality of routing. Partial Route is the first algorithm capable of handling systems of arbitrary topology containing an arbitrary number of faults. The worst-case performance of the algorithm in an n-node system, is shown to be optimal when k = n - 1 and within a factor of 2 of optimal when k = 1. Simulation results on meshes and hypercubes are also presented that show, in the average case, Algorithm Partial Route is nearly optimal for relatively small values of k. (C) 1995 Academic Press, Inc.