Increasing NoC Performance and Utilisation using a Dual Packet Exit Strategy

When designing a network the use of buffers is inevitable. Buffers are used at the entry point, inside and at the exits of the network. The usage of these buffers significantly changes the performance of the system as a whole. In order to enhance the buffer utilisation the concept of letting more than one packet exit the network at every switch each clock cycle is introduced - Dual Packet Exit (DPE). The approach is tried on a 4 x 4 and a 6 x 6 mesh. We demonstrate the buffers used in combination with different routing strategies for best effort performance. The result we present shows a 50 % reduction in terms of worst case latency and a 30 % reduction in terms of average latency as well as an increased throughput both from a system and network perspective. We define the term Operational Efficiency as a measure of the network efficiency and show that it increases by roughly 20 % with the DPE technique.