The latency through the NoC comprises two components:
- Structural latency
- This is ‘best case latency’ which is the time taken for packets to progress through the pipeline stages inside the NoC.
- Queuing latency
- This is the delay caused by queuing in the network. If a flit from a packet is placed in a queue, the flits ahead of it need to drain out before the flit will be serviced.
It is important to understand the role of queuing latency. Depending on the workload sometimes queuing latency has a much bigger impact on the average transaction latency than structural latency, especially in a heavily loaded system.