Link scheduler for network-on-chip

Wormhole-switching is usually employed in the emerging network-on-chip (NoC), in which the link scheduler can hardly guarantee the packet-level latency. Reverse anchored round-robin (RARR) is proposed as hybrid of the flit-by-flit round-robin (FFRR) and the packet-by-packet round-robin (PPRR). In the scheme of RARR, before the head flits have arrived at the destination, the packets are forwarded flit by flit. Then the scheduler at the destination link starts attempting to mark all fragments of the packet as anchors, which is accomplished by requesting and scheduling following the path reversely and hop by hop. The anchored packet takes priority over others, and will be scheduled at packet level. Others will be scheduled flit by flit only if the anchored one breaks. The RARR is inspired by the anchored round-robin (ARR), but employs more determinate anchoring scheme and eliminates the deadlock in ARR. Familiar round-robin were quantified via a cycle-accurate wormhole network simulator, including FFRR, PPRR, ARR and RARR. The RARR was shown to be most efficient among them.