QoR Dashboard & Trend Triage: Interview Drills

Interview drills

Interview Drills for QoR Dashboard & Trend Triage focuses on WNS/TNS trend, area delta, dynamic/leakage trend, compile runtime. The goal is to connect observed QoR movement to mechanism, ownership, and regression risk.

PROMPT
You observe WNS/TNS trend, area delta, dynamic/leakage trend, compile runtime in QoR Dashboard & Trend Triage. Walk through root cause and closure plan.

STRONG ANSWER
1. Names run context and affected QoR lane.
2. Explains QoR closure is a trend-management problem: dashboard baselines catch regressions early and keep optimization decisions tied to measurable outcomes.
3. Requests QoR dashboard snapshot, baseline diff, closure memo.
4. Proposes one reversible fix and full regression scope.

WEAK ANSWER
Jumps to random tool switches without mechanism evidence.

Whiteboard diagram

QoR dashboard lanes

QOR DASHBOARD
timing lane : WNS / TNS / endpoint count
area lane   : cell area / buffer %
power lane  : dynamic / leakage / clock %
runtime lane: compile time / memory

Root-cause narration

ROOT-CAUSE TREE — QoR Dashboard & Trend Triage

WNS/TNS trend, area delta, dynamic/leakage trend, compile runtime regressed
        |
   same RTL/constraints tag?
     /              \
   no                yes
   |                  |
input drift      transform side-effect
 /    \             /         \
SDC    libs      mapping      physical estimate
diff   diff      choice       mismatch

Synthesis deep dive

Constraint hygiene determines whether synthesis QoR is trustworthy.

Concept diagram

CONSTRAINT FLOW

RTL intent -> synthesis SDC -> compile checks -> QoR dashboard -> review gate

Metric graph

QOR HEALTH

constraint lint pass   ███████████████
unconstrained count    ███
policy violations      ██

Reports and artifacts

• compile QoR

• unconstrained endpoints

• constraint lint

• policy audit log

Mini case study

Nightly WNS improved but unconstrained paths jumped; strict SDC lint restored true QoR picture.

Debug branches

• Diff SDC first

• Audit dont_touch scope

• Track unconstrained trend weekly

Senior review question

Ask: what evidence proves this QoR move is real and stable?

Key takeaways

• State exact run context (RTL, SDC, libs, switches) with every QoR claim.

• Re-run timing, area, and power regressions after each synthesis ECO.

Common pitfalls

• Comparing runs with mismatched constraints or library views.

• Timing-only fixes that violate power or area budgets.

• Skipping equivalence checks after structural changes.

Principal synthesis review addendum

QoR closure is a trend-management problem: dashboard baselines catch regressions early and keep optimization decisions tied to measurable outcomes.

Metric: WNS/TNS trend, area delta, dynamic/leakage trend, compile runtime