Low Overhead Predictability Enhancement in Non-preemptive Network-On-Chip Routers using Priority Forwarded Packet Splitting

Providing predictability enhancement for NoC packets can be a difficult proposition when dealing with simple non-preemptive designs primarily due to occurrence of head of line blocking and tail backing of high priority packets as a result of lower priority packets. Typically, predictability is enhanced by making the NoC preemptive by the use of Virtual Channels or employing techniques like Time Division Multiplexing which are generally expensive. This paper presents a low overhead predictability enhancement approach for non-preemptive NoCs which utilises low overhead techniques to resolve head of line blocking and tail backing. As per the technique, head of line blocking is resolved by enabling the low priority packet causing the block to inherit the priority of the blocked high priority packet while tail backing is resolved by splitting the low priority packet that cause the tailback. We then demonstrate the effectiveness of the technique using a prototype and evaluate the implementation overhead.