Analysis of a 3D toroidal network for a shared memory architecture

Horizon is a shared-memory multiple-instruction-stream-multiple-data-stream architecture currently under development. A synchronized network model suitable for this architecture is described. The model is defined in terms of a topology and routing policy. A three-dimensional toroidal topology is investigated for its multiple redundant paths, memory locality, and simplicity in both routing and construction. The routing policy is based on a desperation routing scheme in which it is not guaranteed that a message will make progress on a given network cycle. This scheme requires no complex deadlock avoidance algorithms or node-to-node flow control, allowing a very simple and efficient implementation. Design considerations and preliminary performance results are discussed