A Round-Robin Scheduling Strategy for Reduced Delays in Wormhole Switches with Virtual Lanes

摘要

The forwarding of flits from one switch to another in wormhole networks with virtual lanes is typically accomplished using Flit-by-Flit Round-Robin (FFRR) scheduling. This paper presents the Anchored Round-Robin (ARR) scheduling discipline, which preserves the throughput characteristics of FFRR while significantly reducing the average delay experienced by packets. The ARR scheduler achieves the lower average delay by attempting to trasmit all flits of a packet before beginning the transmission of flits from another packet. The ARR scheduler is idle only when there are no flits to transmit, thus achieving the same throughput characteristics as FFRR. This paper further presents a simulation-based analysis of the ARR scheduler, and the dependence of the performance obtained on the offered load and the packet lengths.