PPA success is a workload-aware contract bounded by modes and corners. Implementation and verification teams must be able to validate it independently.
System budgets fail when block contracts and margins stay implicit. Every delta needs an owner, a confidence level and a rollback trigger.
As a workload-aware contract with mode and corner bounds that other teams can validate on their own. A peak benchmark uplift without bounds is not a target.
Because assumptions never decomposed into owned block contracts with explicit margin accounting. Integration then discovers every optimistic share at once.
Baseline, requested delta, accepted delta, confidence, owner, affected domains and rollback trigger. Final numbers alone cannot be renegotiated when assumptions move.
Ledger field | Purpose | Missing symptom |
|---|---|---|
Baseline and delta | Names what changed | Arguments about whose number moved |
Confidence and owner | Prices the uncertainty | Orphaned risks nobody defends |
Rollback trigger | Bounds the experiment | Irreversible commitments under doubt |
Floorplan-unaware architecture shows up as critical interfaces routed across congestion. Trial floorplan evidence should arrive before RTL commits, not after.
Power delivery bounds sustainable frequency and concurrency. Dynamic power follows capacitance times voltage squared times frequency, so voltage choices dominate the budget.
Critical interfaces needing long cross-die routes through known congestion corridors. Adjacency is an architecture input, not a backend surprise.
They cap sustainable frequency and concurrency, which bounds how aggressive the microarchitecture may be. Assuming later DVFS absorbs ambition is planning against physics.
Each crossing adds latency, protocol complexity and verification burden that can erase the PPA gain it was meant to enable. Crossings are architecture, not detail.
Dynamic power from stated parameters
formula: P = C x V^2 x f
example: switched capacitance 2 nF, supply 0.8 V, frequency 3 GHz
result: 2e-9 x 0.64 x 3e9 = 3.84 W dynamic for this blockThe memory bandwidth roof comes from pins, DRAM type, fabric links and coherence overhead together. Datasheet peak alone overstates usable throughput.
A signoff blocker lacks credible containment. A tracked risk has an owner, measurable bounds and scheduled mitigation, which is why the two must never merge in reports.
Pin count and DRAM transfer rate bound the entry, while fabric links, read-write turnaround and coherence overhead take their cut. A numeric estimate states each term, not the datasheet line.
A blocker has no credible containment. A tracked risk has an owner, measurable boundaries and dated mitigation. Treating blockers as tracked risks ships unknown exposure.
Critical assumptions validated, residual risks bounded and owned, and downstream gate criteria agreed across physical design, power and verification. Schedule pressure is never a criterion.
DRAM bandwidth roof from stated parameters
formula: BW = channels x bytes_per_transfer x transfer_rate
example: 4 channels, 32-bit interface, 6400 megatransfers per second
result: 4 x 4 x 6.4e9 = 102.4 GB/s peak before fabric and protocol lossesNegotiate macro placement or topology change with data, or accept the frequency target change explicitly. Ignoring physical feedback is not an option on the table.