Fabric Contention Debug: Reports & Metrics

Reports and metrics

Reports & Metrics 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.

The job of a report is to convert contention hotspot recurrence, throughput collapse trigger into a closure decision. One summary number is never enough without baseline, owner, and boundary context.

Metric movement

METRIC GRAPH — contention hotspot recurrence, throughput collapse trigger

integration confidence
  ^
  |                         target
  |                       - - - - - - -
  |                  o post-fix + regression
  |              o
  |         o baseline
  |    o failing run
  +--------------------------------------> closure iteration
    baseline freeze   owner fix   full matrix

Readout:
  - compare results on the same manifest baseline
  - state owner and boundary with every metric movement

Risk distribution

RISK HISTOGRAM — Fabric Contention Debug

issue count
  |      ***
  |    *******
  |  ***********
  |*************  <- critical tail
  +--------------------> risk severity
   low   medium   high

Debug the high-severity tail first; averages hide escape risk.

• Track contention hotspot recurrence, throughput collapse trigger by domain and owner boundary.

• Store baseline manifest beside every metric snapshot.

• Report both immediate fix result and full regression result.

• Explicitly call out residual risk and ownership.

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.

Reading integration reports