fix(launcher): increase Nemotron 3.5 Lightning QAD parallelism

[jenchen13]

What does this PR do?

Type of change: Bug fix

Current Nemotron 3.5 Lightning QAD example can OOM, and also TP=2 is not supported for static quantization. Increase GPUs, CP and decrease TP=1

Usage

# Add a code snippet demonstrating how to use this

Testing

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Additional Information

Summary by CodeRabbit

• Configuration
  • Updated the QAD training setup to run across four nodes with revised tensor and context parallelism settings.
  • Documented the 32K sequence-length constraint and removed outdated run information.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Plan: Enterprise

Run ID: 4de141d4-7600-43a4-94cf-472e1d05fda5

📥 Commits

Reviewing files that changed from the base of the PR and between ddca53b and d0854be.

📒 Files selected for processing (1)

• tools/launcher/examples/nvidia/NVIDIA-Nemotron-3.5-Lightning-30B-A3B-BF16/megatron_lm_qad.yaml

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📝 Walkthrough

Walkthrough

The QAD launcher example now documents and configures four B200 nodes with TP=1 and CP=4. It also documents the 8K-per-rank context constraint.

Changes

QAD topology

Layer / File(s)	Summary
QAD topology configuration tools/launcher/examples/nvidia/NVIDIA-Nemotron-3.5-Lightning-30B-A3B-BF16/megatron_lm_qad.yaml	The documented and applied QAD topology changes from 2 nodes with TP=2 and CP=1 to 4 nodes with TP=1 and CP=4. The comments add the 8K-per-rank context constraint and remove the previous 524,288-token run note.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to d0854

This PR adjusts the Nemotron 3.5 Lightning QAD launcher configuration to use more GPUs and different parallelism settings; no actionable merge-blocking risk remains beyond normal checks and review.

Possibly related PRs

• NVIDIA/Model-Optimizer#2179: Updates the same QAD launcher configuration and distributed topology settings.

Suggested reviewers: kevalmorabia97, aanoosheh

🚥 Pre-merge checks | ✅ 6

✅ Passed checks (6 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: increasing Nemotron 3.5 Lightning QAD parallelism.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Security Anti-Patterns	✅ Passed	The diff changes only one YAML launcher file; it adds no Python, dependency, torch.load, numpy.load, trust_remote_code, eval/exec, or # nosec patterns.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch jennifchen/update_lightning

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.80%. Comparing base (ddca53b) to head (d0854be).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2191      +/-   ##
==========================================
+ Coverage   78.77%   78.80%   +0.03%     
==========================================
  Files         522      522              
  Lines       60461    60461              
==========================================
+ Hits        47629    47648      +19     
+ Misses      12832    12813      -19     

Flag	Coverage Δ
regression	14.89% <ø> (+0.06%)	⬆️
unit	55.30% <ø> (ø)

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[github-actions]

PR Preview Action v1.8.1
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2026-08-14 19:09 UTC