Designing Energy-Efficient Low-Diameter On-chip Networks with Equalized Interconnects

Abstract

In a power and area constrained multicore system, the on-chip communication network needs to be carefully designed to maximize the system performance and programmer productivity while minimizing energy and area. In this paper, we explore the design of energy-efficient low-diameter networks (flattened butterfly and Clos) using equalized on-chip interconnects. These low-diameter networks are attractive as they can potentially provide uniformly high throughput and low latency across various traffic patterns, but require efficient global communication channels. In our case study, for a 64-tile system, the use of equalization for the wire channels in low-diameter networks provides 2x reduction in power with no loss in system performance compared to repeater-inserted wire channels. The use of virtual channels in routers further reduces the power of the network by 25-50% and wire area by 2x.