Extended case study

A release review reports operational intensity, achieved TOPS, and bandwidth utilization regression tied to Memory Bandwidth & Roofline.

Background

Previous model/run was acceptable; new changes improved one KPI but harmed another production-critical objective.

Symptoms observed

• operational intensity, achieved TOPS, and bandwidth utilization degraded

• Cross-team disagreement on root cause

• Inconsistent behavior across datasets/workloads

Investigation timeline

1. Hour 0: freeze data, model, runtime, and hardware revision tags

2. Hour 1: isolate first failing workload slice

3. Hour 2: validate data integrity and metric pipeline

4. Hour 3: profile compute/memory/runtime path

5. Hour 4: classify algorithm vs mapping vs stack issue

6. Hour 5: deploy minimal reversible patch

7. Hour 6: run validation + shadow deployment checks

Root cause

Kernel was bandwidth-bound, so compute-focused optimization showed minimal gain; memory tiling fix unlocked throughput.

Fix and validation

• Bounded fix with explicit owner

• Re-run roofline plot, kernel profile report, and memory traffic breakdown

• Validate against production-aligned KPI gates

Lessons learned

• Use multi-layer evidence, not single dashboard metrics

• Keep rollback path ready

• Tie model quality to engineering impact

CASE STUDY — Memory Bandwidth & Roofline
quality / latency / power / confidence trend

System under stress

TRAINING TIMELINE — Memory Bandwidth & Roofline

time --->
data batch      __/--/--/--/--/--/--/--
forward pass    ____/--/--/--/--/--/---
backward pass   ________/--/--/--/-----
optimizer step  ____________/--/--/----
eval checkpoint _____________/--/-------

Convergence depends on stable loop timing and signal quality.

AI-VLSI deep dive

Throughput claims are meaningless without roofline and bandwidth context.

Concept diagram

COMPUTE ANALYSIS

workload profile -> roofline -> precision policy -> target silicon

Metric graph

EFFICIENCY DRIVERS

compute utilization    ██████
memory utilization     █████████
precision efficiency   ███████

Reports and artifacts

• platform benchmark matrix

• roofline chart

• precision sweep

• latency/power dashboard

Mini case study

Kernel optimization shifted from compute tuning to memory tiling after roofline analysis.

Debug branches

• Classify compute vs memory bound

• Compare precision tiers

• Align platform to SLA

Senior review question

Ask: what evidence connects this ML claim to a concrete VLSI workflow decision and owner signoff?

Key takeaways

• Every AI claim should map to a measurable engineering outcome.

• Validate both model quality and hardware/runtime feasibility before adoption.

Common pitfalls

• Optimizing benchmark metrics that do not correlate with signoff goals.

• Ignoring data drift and calibration after deployment.

• Shipping ML workflows without clear rollback ownership.

Execution drill pack 1

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 1

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 2

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 2

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 3

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 3

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 4

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 4

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 5

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 5

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 6

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 6

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 7

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 7

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 8

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 8

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 9

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 9

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 10

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 10

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 11

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 11

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 12

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 12

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Execution drill pack 13

Use this pack to rehearse AI-for-VLSI decision making on ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded: metric framing, mechanism proof, hardware implications, and release safety.

Evidence checklist

• Metric context includes workload, dataset slice, and revision tags.

• Mechanism explanation links model behavior to observed outcome.

• Hardware/runtime feasibility is profiled, not assumed.

• Owner and rollback path are documented before rollout.

Review prompts

1. Which decision will this model output influence?

2. What is the first failing layer when metric regresses?

3. Which owner applies the smallest reversible fix?

4. What validation matrix is required before deployment?

Evidence capsule

AI-VLSI EVIDENCE CAPSULE 13

PATH: ai-vlsi/ai-compute-hardware/memory-bandwidth-and-roofline/case-study-expanded
WORKLOAD SLICE: <name>
PRIMARY METRIC: <value/trend>
FIRST FAILING LAYER: <data/model/runtime/hardware>
OWNER: <name>
PRIMARY ARTIFACT: <report/profile/dashboard>
DECISION: <ship / rollback / escalate>

Principal AI-VLSI review addendum

Roofline analysis links arithmetic intensity to memory bandwidth limits, exposing whether kernels are compute-bound or memory-bound.

Metric: operational intensity, achieved TOPS, and bandwidth utilization