MoDe-X: Microarchitecture of a Layout-Aware Modular Decoupled Crossbar for On-Chip Interconnects

The number of cores in a single chip keeps increasing with process technology scaling, requiring a scalable interconnection network topology. Buffered wormhole-switched interconnect architectures are attractive for such multicore architectures. The 2D mesh on-chip interconnect provides a scalable, cost-efficient, flexible, and reliable next-generation interconnect topology in this context. In this paper, we provide a microarchitecture for a power and area efficient router for a 2D mesh interconnect. We propose an efficient crossbar implementation, called MoDe-X, that uses a reasonable power-performance tradeoff. The MoDe-X router uses a Modular-Decoupled Crossbar (MoDe-X) that incorporates dimensional decomposition and segmentation to achieve power and area savings. However, unlike most prior work that considers only logical representation of the crossbars, MoDe-X is a physically aware router accounting for the actual layout of router components to reflect practical design requirements. Our simulation results and power estimate show that the MoDe-X router architectures can reduce the overall router area by up to 40 percent and power consumption by up to 35 percent with very little performance impact that occurs only at higher loads. Further, by applying aggressive power gating techniques the net power reductions can be as much as 99 percent for some workloads with no additional performance impact.