JoshuaandCursor 1030791f53 Fix distributed AutoQuantize scoring and share backward setup (#2231)
### What does this PR do?

Type of change: Bug fix

AutoQuantize can measure a group of quantized expert layers at their
enclosing MLP output. That enclosing module is often a plain PyTorch
container and does not carry distributed-group information, so its
sensitivity score was not combined across data- or expert-parallel
workers.

This PR obtains the distributed groups from the quantized layers when
the scoring module does not provide them. It also preserves construction
order for quantized modules, scoring modules, and their registered
hyperparameters so every worker accumulates scores in the same order.

The temporary state needed by backward-based scoring is now managed by
one shared session. The session installs and removes forward patches and
invocation-specific output-gradient hooks, controls parameter gradients,
and restores the active quantization recipes even when scoring raises an
exception. Scoring methods remain responsible for their own score
calculation.

### Usage

N/A — this fixes existing AutoQuantize behavior and does not add an API
or flag.

### Testing

- `pre-commit run --files modelopt/torch/quantization/algorithms.py
tests/unit/torch/quantization/test_autoquant.py`
- `pytest -q tests/unit/torch/quantization/test_autoquant.py` — 102
passed
- Added a real two-rank gradient AutoQuantize test covering MoE experts
scored at an enclosing MLP.
- Added regressions for deterministic hyperparameter registration,
per-invocation replay for reused score modules, exact
`forward`-attribute restoration, partial setup rollback, and cleanup
after a scoring failure.

### Before your PR is "*Ready for review*"

Make sure you read and follow [Contributor
guidelines](https://github.com/NVIDIA/Model-Optimizer/blob/main/CONTRIBUTING.md)
and your commits are signed (`git commit -s -S`).

Make sure you read and follow the [Security Best
Practices](https://github.com/NVIDIA/Model-Optimizer/blob/main/SECURITY.md#security-coding-practices-for-contributors).

- Is this change backward compatible?: ✅ — no API or checkpoint format
changes; distributed sensitivity values now include the missing
reduction.
- If you copied code from any other sources or added a new PIP
dependency, did you follow guidance in `CONTRIBUTING.md`: N/A
- Did you write any new necessary tests?: ✅
- Did you update
[Changelog](https://github.com/NVIDIA/Model-Optimizer/blob/main/CHANGELOG.rst)?:
N/A — no new feature, deprecation, breaking change, or critical
release-note item.
- Did you get Claude approval on this PR?: ❌ — pending review.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Bug Fixes**
* Improved quantization scoring consistency through deterministic
ordering and invocation handling.
* Added more reliable distributed score aggregation, including support
for mixture-of-experts models.
* Improved gradient-based scoring for repeated evaluations, tuple
outputs, and checkpoint-compatible workflows.
* Ensured model behavior and scoring state are restored after successful
or failed evaluations.
  * Avoided unnecessary output replay when gradients are not required.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: Joshua Hill <joshua.hill@baseten.co>
Co-authored-by: Cursor <cursoragent@cursor.com>
2026-09-13 14:55:32 +00:00
2026-09-10 17:30:37 +00:00
2026-09-10 17:30:37 +00:00
2026-09-10 17:30:37 +00:00
2026-09-10 00:35:31 +08:00
2026-09-10 17:30:37 +00:00

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NVIDIA Model Optimizer

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NVIDIA Model Optimizer (referred to as Model Optimizer, or ModelOpt) is a library comprising state-of-the-art model optimization techniques including quantization, pruning, Neural Architecture Search (NAS), distillation, speculative decoding and sparsity to accelerate models.

[Input] Model Optimizer currently supports inputs of a Hugging Face, PyTorch or ONNX model.

[Optimize] Model Optimizer provides Python APIs for users to easily compose the above model optimization techniques and export an optimized quantized checkpoint. Model Optimizer is also integrated with NVIDIA Megatron-Bridge, Megatron-LM and Hugging Face Accelerate for training required inference optimization techniques.

[Export for deployment] Seamlessly integrated within the NVIDIA AI software ecosystem, the quantized checkpoint generated from Model Optimizer is ready for deployment in downstream inference frameworks like SGLang, TensorRT-LLM, TensorRT, or vLLM. The unified Hugging Face export API now supports both transformers and diffusers models.

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To install stable release packages for Model Optimizer with pip from PyPI:

pip install -U nvidia-modelopt[all]

Model Optimizer will download and install additional third-party open source software projects. Review the license terms of these open source projects before use.

To install from source in editable mode with all development dependencies or to use the latest features, run:

# Clone the Model Optimizer repository
git clone git@github.com:NVIDIA/Model-Optimizer.git
cd Model-Optimizer

pip install -e .[dev]

You can also directly use NVIDIA container images, which have Model Optimizer pre-installed:

  • nvcr.io/nvidia/pytorch:<version>-py3
  • nvcr.io/nvidia/nemo:<version>
  • nvcr.io/nvidia/tensorrt-llm/release:<version>

Before pulling and using the container images, please review their respective license terms. Make sure to upgrade Model Optimizer to the latest version as described above. Visit our installation guide for more fine-grained control on installed dependencies or for alternative docker images and environment variables to setup.

Techniques

Technique Description Examples Docs
Post Training Quantization Compress model size by 2x-4x, speeding up inference while preserving model quality! [HF LLMs / VLMs] [Megatron-Bridge LLMs / VLMs] [Diffusers] [ONNX] [Windows] [docs]
Quantization Aware Training / Distillation Refine accuracy of quantized models even further with a few training steps! [Hugging Face] [Megatron-Bridge] [docs]
Pruning Reduce your model parameters or memory footprint and accelerate inference by removing unnecessary weights! [General] [Megatron-Bridge]
Distillation Reduce deployment model size by teaching small models to behave like larger models! [Hugging Face] [Megatron-Bridge] [Megatron-LM] [docs]
Speculative Decoding Train draft modules to predict extra tokens during inference! [Hugging Face] [Megatron-LM] [docs]
Sparsity Efficiently compress your model by storing only its non-zero parameter values and their locations [Hugging Face] [docs]

Pre-Quantized Checkpoints

Resources

Model Support Matrix

Model Type Support Matrix
LLM / VLM Quantization View Support Matrix
Diffusers Quantization View Support Matrix
ONNX Quantization View Support Matrix
Windows Quantization View Support Matrix
Quantization Aware Training View Support Matrix
Pruning View Support Matrix
Distillation View Support Matrix
Speculative Decoding View Support Matrix

Deprecation Policy

Model Optimizer follows a structured approach to managing deprecated features:

  • Communication: Deprecation notices are documented in the Changelog. Deprecated items include source code statements indicating deprecation timing, with runtime warnings issued upon use.
  • Migration Period: Since Model Optimizer is still pre-1.0, we provide a 1-release (~1-month) migration period after deprecation. During this window, deprecated features continue functioning while issuing warnings.
  • Scope: The policy addresses both complete deprecations (entire APIs removed) and partial ones (specific parameters removed while methods remain).
  • Removal: Following the migration period, deprecated elements are removed in alignment with semantic versioning standards, potentially including breaking changes in minor version updates while Model Optimizer remains in 0.x.

Citation

If you use NVIDIA Model Optimizer in your research, please cite it as follows:

@misc{nvidia-modelopt,
  author       = {{NVIDIA Corporation}},
  title        = {{NVIDIA Model Optimizer}},
  howpublished = {\url{https://github.com/NVIDIA/Model-Optimizer}},
  year         = {2024--2026},
  note         = {GitHub repository}
}

Contributing

Model Optimizer is now open source! We welcome any feedback, feature requests and PRs. Please read our Contributing guidelines for details on how to contribute to this project.

AI Agents

ModelOpt's agent skills can be installed from this repository and used in any workspace.

Claude Code

claude plugin marketplace add https://github.com/NVIDIA/Model-Optimizer.git
claude plugin install modelopt@modelopt

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codex plugin marketplace add https://github.com/NVIDIA/Model-Optimizer.git

Then open /plugins, select the modelopt marketplace, and install modelopt. Contributors can also use the skills directly from a checkout. See the agent tooling notes.

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