Worked example

Worked Example 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.

A weekly compile reports WNS/TNS trend, area delta, dynamic/leakage trend, compile runtime regression. Instead of random knob tuning, start by proving whether input context changed and which mechanism dominates.

Sequence under inspection

SYNTHESIS FLOW — QoR Dashboard & Trend Triage

RTL + constraints
      |
      v
elaboration + checks
      |
      v
mapping + optimization
      |
      v
QoR reports (timing/area/power)
      |
      v
incremental ECO + regression

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

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

1. Capture baseline and regressed artifact pair.

2. Confirm manifest parity (RTL, SDC, libs, switches).

3. Pin first metric drift and mechanism hypothesis.

4. Reproduce with QoR dashboard snapshot, baseline diff, closure memo.

5. Apply one reversible fix and run matrix regression.

Did the fix hold?

BEFORE / AFTER QOR — QoR Dashboard & Trend Triage

QoR score
  0 |                     --- target zone
 -1 |        ● regression
 -2 |             ● baseline
 -0.5|                  ● after fix
    +----------------------------------> iteration

Validate timing + area + power, not one number.

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