Performance Counters (PMC): Review Checklist

Review checklist

Review Checklist for Performance Counters (PMC) centers on counter fidelity, sampling overhead, and triage turnaround time. Tie every claim to a measurable artifact and an owner-controlled action.

• Workload scope and KPI targets are explicit.

• Environment metadata is locked and reproducible.

• Stage-loss classification is backed by evidence.

• Owner and rollback conditions are documented.

• Validation matrix covers perf, correctness, and power.

• Owners signed: silicon performance lead, firmware owner, tooling owner.

CPU deep dive

Physical closure and observability planning determine whether CPU architecture wins survive first silicon.

Concept diagram

CPU SILICON CLOSURE

core/LLC floorplan -> clock/power domains -> PMCs/observability -> bring-up

Metric graph

CLOSURE RISK MIX

timing margin risk   █████
thermal hotspots     ████
bring-up blockers    ███

Reports and artifacts

• floorplan congestion map

• timing closure summary

• IR/thermal transient report

• bring-up milestone tracker

Mini case study

A floorplan change improved routing congestion but created thermal clustering that forced frequency throttling in sustained tests.

Debug branches

• Trace critical paths to physical regions and domain crossings

• Run dynamic IR and thermal checks on burst workloads

• Use PMCs and bring-up logs to correlate silicon symptoms to design intent

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.

Review checklist explanation

A checklist here prevents false confidence. Every item should defend against a known closure failure mode.

For Performance Counters (PMC), minimum checklist: workload scope, counter fidelity, sampling overhead, and triage turnaround time, artifact evidence (PMU event map, counter correlation notebook, and anomaly triage report), bottleneck class, owner, rollback path, and full-matrix validation.

If architecture or RTL changed, include correctness, power, timing, and observability checks. If software policy changed, include compatibility and deployment safety evidence.