Achieving Flexible Global Reconfiguration in NoCs Using Reconfigurable Rings

Abstract

The communication behaviors in NoCs of chip-multiprocessors exhibit great spatial and temporal variations, which introduce significant challenges for the reconfiguration in NoCs. Existing reconfigurable NoCs are still far from ideal reconfiguration scenarios, in which globally reconfigurable interconnects can be immediately reconfigured to provide bandwidths on demand for varying traffic flows. In this paper, we propose a hybrid NoC architecture that globally reconfigures the ring-based interconnect to adapt to the varying traffic flows with a high flexibility. The ring-based interconnect has the following advantages. First, it includes horizontal rings and vertical rings, which can be dynamically combined or split to provide low-latency channels for heavy traffic flows. Second, each combined ring connects a number of nodes, thereby improving both the utilization of each ring and the probability to reuse previous reconfigurable interconnects. Finally, the reconfiguration algorithm has a linear-time complexity and can be implemented using a low-overhead hardware design, making it possible to achieve a fast reconfiguration in NoCs. The experimental results show that compared to recent reconfigurable NoCs, the proposed NoC architecture can greatly improve the saturation throughput for synthetic traffic patterns, and reduce the packet latency over 40 percent for realistic benchmarks without incurring significant area and power overhead.