The Y-architecture: yet another on-chip interconnect solution

In this paper, we propose a new on-chip interconnect scheme called Y-architecture, which can utilize the on-chip routing resources more efficiently than traditional Manhattan interconnect architecture by allowing wires routed in three directions (0°, 60°, and 120°). To evaluate the efficiency of different interconnect architectures, we assume mesh structures with uniform communication demand and develop a multi-commodity flow (MCF) approach to model the on-chip communication traffic. We also extend the combinatorial MCF algorithm of N. Garg and J. Konemann (Proc. 39th Annual Symp. on Foundations of Comp. Sci., pp. 300-309, 1998) to compute the optimal routing resource allocations for different interconnect architectures. The experiments show that: (1) compared with the Manhattan architecture, the Y-architecture demonstrates a throughput improvement of 30.7% for a square chip. The throughput of the Y-architecture is only 2.5% smaller than that of the X-architecture. (2) A chip with the shape of a convex polygon produces better throughput than a rectangular chip: For Y-architecture, a hexagonal chip provides 41% more throughput than a squared chip using the Manhattan architecture. For Manhattan architecture, a diamond chip achieves a throughput improvement of 19.5%, over the squared chip using the same interconnect architecture. (3) Compared with Manhattan architecture, the Y-architecture reduces the wire length of a randomly distributed two pin net by 13.4% and the average wire length of Y-architecture is only 4.3% more than that of the X-architecture.