A Wormhole NoC Protocol for Mixed Criticality Systems

Lack of scalability and difficulties in predicting the temporal behaviour of bus-based architectures has lead to the development of Network-on-Chip (NoC) protocols that provide a schedulable resource for moving data across multi-core platforms. Wormhole switching and credit-based flow control protocols have been used to support flit-level priority-preemptive link arbitration in NoCs, which leads to analysable temporal behaviour. In this paper we develop a new protocol (WPMC), based on the same family of protocols, that gives full support to mixed-criticality on-chip communications. WPMC is defined to give adequate partitioning between criticality levels, and to use resources efficiently. Analysis is developed and implementation aspects are considered. A cycle accurate simulator is used for scenario-based verification, and the effectiveness of the protocol and its scheduling model is evaluated via message-set generation.