A priority-based flow control mechanism to support real-time traffic in pipelined direct networks

Real-time extensions to wormhole routing (WR), with multiple virtual channels, and priority based physical link arbitration and virtual channel (VC) allocation, have been proposed in the literature. With a fixed number of VCs/link, a message can face an unbounded priority inversion, rendering the global priority order ineffective. We propose a new flow control mechanism called preemptive pipelined circuit switching for real-time messages (PPCS-RT) to reduce the priority inversion problem. PPCS-RT outperforms WR with the performance difference being largest with 1 VC/link. The difference in overall miss ratio is over 30% with 1 VC.