Highway in TDM NoCs

Abstract

TDM (Time Division Multiplexing) is a well-known technique to provide QoS guarantees in NoCs. However, unused time slots commonly exist in TDM NoCs. In the paper, we propose a TDM highway technique which can enhance the slot utilization of TDM NoCs. A TDM highway is an express TDM connection composed of special buffer queues, called highway channels (HWCs). It can enhance the throughput and reduce data transfer delay of the connection, while keeping the quality of service (QoS) guarantee on minimum bandwidth and in-order packet delivery. We have developed a dynamic and repetitive highway setup policy which has no dependency on particular TDM NoC techniques and no overhead on traffic flows. As a result, highways can be efficiently established and utilized in various TDM NoCs. According to our experiments, compared to a traditional TDM NoC, adding one HWC with two buffers to every input port of routers in an 8×8 mesh can reduce data delay by up to 80% and increase the maximum throughput by up to 310%. More improvements can be achieved by adding more HWCs per input per router, or more buffers per HWC. We also use a set of MPSoC application benchmarks to evaluate our highway technique. The experiment results suggest that with highway, we can reduce application run time up to 51%.