Physical Design, Perf & Bring-up: Tricky Q&A

[INT][CPU][CPU-PHYSICAL-VERIFICATION]

Q: How do you close Core Array Floorplanning when wirelength congestion index, macro adjacency quality, and frequency headroom regresses?

A:
Name the failing workload, isolate first stage loss, explain mechanism (Core clusters, LLC slices, and interconnect macros must be placed for routability and locality; poor macro adjacency increases delay, congestion, and closure churn.), request floorplan snapshot, congestion heatmap, and timing path locality report, assign owners (physical design lead, CPU architect, implementation owner), and define bounded fix plus rollback-safe validation.

FOLLOW-UP TRAP: Giving generic CPU tuning without workload evidence, owner, or risk controls.

[INT][CPU][CPU-PHYSICAL-VERIFICATION]

Q: How do you close Clock/Power Domains (CPU) when clock skew budget usage, CDC/RDC violation count, and power-state transition stability regresses?

A:
Name the failing workload, isolate first stage loss, explain mechanism (Clock and power partitioning enables frequency and energy scaling, but every domain crossing adds synchronization, reset sequencing, and intent verification burden.), request clock tree partition map, UPF/CPF intent review, and CDC-RDC signoff report, assign owners (clock architect, low-power architect, SoC integration lead), and define bounded fix plus rollback-safe validation.

FOLLOW-UP TRAP: Giving generic CPU tuning without workload evidence, owner, or risk controls.

[INT][CPU][CPU-PHYSICAL-VERIFICATION]

Q: How do you close Performance Counters (PMC) when counter fidelity, sampling overhead, and triage turnaround time regresses?

A:
Name the failing workload, isolate first stage loss, explain mechanism (PMCs expose stall classes and throughput limits; the value comes from event taxonomy quality, synchronized sampling, and disciplined correlation against workload traces.), request PMU event map, counter correlation notebook, and anomaly triage report, assign owners (silicon performance lead, firmware owner, tooling owner), and define bounded fix plus rollback-safe validation.

FOLLOW-UP TRAP: Giving generic CPU tuning without workload evidence, owner, or risk controls.

[INT][CPU][CPU-PHYSICAL-VERIFICATION]

Q: How do you close Silicon Bring-up (CPU) when time-to-first-boot, bring-up blocker count, and post-silicon closure velocity regresses?

A:
Name the failing workload, isolate first stage loss, explain mechanism (Bring-up sequences rails, reset, clocks, firmware, and memory training while enabling subsystems incrementally so failures are isolated with maximum observability.), request bring-up checklist, boot log timeline, and failure triage tracker, assign owners (bring-up lead, firmware owner, validation team), and define bounded fix plus rollback-safe validation.

FOLLOW-UP TRAP: Giving generic CPU tuning without workload evidence, owner, or risk controls.

WORKLOAD -> STAGE LOSS -> METRIC -> MECHANISM -> FIX -> REGRESSION

CPU SILICON CLOSURE

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