Fabric Contention Debug: Inputs & Outputs

Inputs and outputs contract

Inputs & Outputs for Fabric Contention Debug focuses on contention hotspot recurrence, throughput collapse trigger. The goal is to map symptoms to boundary contracts, owner actions, and regression-proof closure.

Treat these as a signed integration contract. Ambiguity here causes multi-team debug loops where everyone is right inside their own assumptions.

INPUTS
  - baseline manifest (versions + hashes)
  - interface/budget contract revision
  - mode assumptions (functional/test/low-power)
  - owner accountability map

OUTPUTS
  - measurable closure deltas
  - owner-approved fix proposal
  - regression evidence package
  - risk/waiver disposition

Integration sequence

SOC INTEGRATION FLOW — Fabric Contention Debug

requirements + budgets
        |
        v
IP handoff + collateral check
        |
        v
integration build + bring-up smoke
        |
        v
cross-domain signoff evidence
        |
        v
tapeout readiness decision

Metric in focus: contention hotspot recurrence, throughput collapse trigger

Ownership map

OWNERSHIP MAP — Fabric Contention Debug

artifact             owner
-----------------    -----------------
primary owner     performance lead
co-owner          fabric owner
review owner      firmware owner

No top-level issue should remain ownerless beyond one review cycle.

SoC deep dive

Fabric correctness and contention behavior must be proven together.

Concept diagram

FABRIC FLOW
masters -> routers/VCs -> slaves + memory

Metric graph

LATENCY TAIL
p50 ███
p95 ██████
p99 ██████████

Reports and artifacts

• NoC contention heatmap

• ordering violation report

• QoS fairness summary

• protocol trace

Mini case study

Bandwidth looked fine at average load, but p99 tail violated SLA due to arbitration starvation.

Debug branches

• Isolate traffic class

• Check ordering assumptions

• Audit arbitration policy

Senior review question

Ask: what baseline, owner, and artifact prove this topic is truly closed?

Key takeaways

• State baseline manifest and owner with every closure metric.

• Run cross-domain regression after every top-level fix.

Common pitfalls

• Comparing results across different manifests.

• Unowned issues slipping through review cycles.

• Waiving risks without expiry and validation plan.

Principal SoC review addendum

Contention debug isolates head-of-line blocking, unfair arbitration, and backpressure loops before over-provisioning bus width or buffers.

Metric: contention hotspot recurrence, throughput collapse trigger