CPU Whiteboard Framework

Whiteboard flow

1. Draw fetch -> decode -> rename -> execute -> retire.
2. Mark failing metric and first stage loss.
3. Add memory/coherence/system interactions if needed.
4. Name proving artifact and owner.
5. Show bounded fix and rollback trigger.

Key takeaways

• Strong answers tie workload symptom to mechanism and owner action.

• Never skip validation and rollback criteria in architecture decisions.

CPU deep dive

CPU closure requires architecture intent, reproducible PMU evidence, and explicit owner accountability.

Concept diagram

workload intent -> pipeline behavior -> measured bottleneck -> owner fix

Metric graph

IPC/CPI trend

Reports and artifacts

• CPI stack report

• counter correlation sheet

• regression dashboard

Mini case study

Pin environment metadata before comparing CPU performance captures.

Debug branches

• Reproduce and isolate before tuning

Senior review question

Ask: which CPI/latency evidence proves this topic is truly closed beyond synthetic benchmarks?

Key takeaways

• Always connect microarchitectural counter changes to product workload outcomes.

• Lock binary, compiler, firmware, and thermal metadata before comparing CPU traces.

Common pitfalls

• Treating average IPC as sufficient proof while ignoring latency tails and outliers.

• Applying predictor or prefetch tweaks without first-failing-stage attribution.

• Declaring closure without reproducible perf, correctness, and power gates.