A Communication Architecture for a Massively Parallel Message-Passing Multicomputer

Abstract

Communication networks stress the distinction between classical and massively parallel architectures. The network is the key for the whole architecture efficiency, while severe technological constraints limit the possible choices. This paper presents forced routing, which is the routing strategy of the MEGA massively parallel architecture. Forced routing is a trade-off between deterministic and randomized routing. In the absence of contention, messages follow one shortest path. As the contention increases, messages are randomly spread in the network. Moreover, the algorithm is quite simple and it only needs minor buffering capacity at each node; thus it is well adapted to hardwired implementation. In this paper, we test the performance of the forced and greedy strategies on a variety of communication patterns representing synchronous and asynchronous algorithms. Finally, we sketch a description of the circuit implementing the forced routing, in order to prove the technical feasibility of this appealing algorithm upon the constraint of a mono-chip node.