Read first: Read the mechanism and worked trace first
An illustrative home has two request contexts. Both are occupied waiting for required peer data. A third request arrives. The model assumes those contexts are required for safe request tracking, and no hidden spill storage exists.
Budget accepted contexts, not just links — decision record
Apply the stated local assumptions; record actual platform values before using this as an implementation checklist.
Decision / observation | Required evidence | Consequence |
|---|---|---|
Third request offered | Two contexts remain occupied | Backpressure or use the supported protocol admission/retry mechanism |
A response indication arrives | Its promised data is still outstanding | Do not free the context from the indication alone |
All obligations for one context retire | Identity can no longer receive a late unresolved message | A slot becomes available under the defined completion rule |
The bottleneck is retained end-to-end transaction contexts, not link transport capacity. A link credit cannot safely create storage for an untracked transaction.
Home assignment may use address ranges, hashing or another topology-specific mapping. The count and placement trade service capacity, state storage, routing distance and traffic balance. Measure latency components and hot spots for the selected workload rather than assuming RN-to-HN distance dominates every system.
If a NoC uses virtual networks, document which held/requested resources its routing and dependency rules separate.
Size buffers and return paths under explicit admission, delivery and fairness assumptions.
High CHI RetryAck/PCrdGrant activity = admission-pressure evidence; correlate Completer resources, routing, credits and offered traffic.