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Model-Optimizer/examples/windows
Shengliang Xu 1cceb950d6 [OMNIML-3689] PTQ quant_cfg semantic correction. Design in doc _quant_cfg.rst (#1094)
### What does this PR do?

#### Summary

Redesigns the `quant_cfg` configuration format in ModelOpt's PyTorch
quantization stack, replacing the previous dict-based format with an
**ordered list of typed `QuantizerCfgEntry` dicts**.

##### Motivation

The old `quant_cfg` dict had several pain points:
- **Ambiguous precedence**: no explicit way to reason about which entry
wins when multiple keys match a quantizer
- **Mixed key namespaces**: wildcard paths and PyTorch class names lived
in the same dict level, requiring ad-hoc dispatch
- **Magic `"default"` key**: an implicit, undocumented catch-all that
was easy to misuse
- **Poor composability**: merging two configs required dict updates that
silently discarded keys
- **No YAML round-trip fidelity**: the nested structure couldn't be
expressed cleanly in YAML

##### New format

`quant_cfg` is now an ordered list of `QuantizerCfgEntry` TypedDicts.
Each entry has:
- `quantizer_name` *(required)*: `fnmatch` wildcard matched against
quantizer module names
- `cfg` *(optional)*: dict (or list of dicts) of
`QuantizerAttributeConfig` fields
- `enable` *(optional)*: toggles quantizer on/off independently of `cfg`
- `parent_class` *(optional)*: restricts match to quantizers whose
parent module is of the given PyTorch class (e.g. `"nn.BatchNorm2d"`)

Entries are applied in list order; later entries override earlier ones.
The canonical pattern is deny-all first (`_base_disable_all`), then
selectively re-enable and configure, then apply standard exclusions
(`_default_disabled_quantizer_cfg`).

##### Changes

**Core library (`modelopt/torch/quantization/`)**

- **`config.py`**:
- Added `QuantizerCfgEntry` TypedDict (line 163) and
`find_quant_cfg_entry_by_path()` helper for exact-match lookup of
entries by path.
- Added `normalize_quant_cfg_list()` (line 1539) that converts legacy
formats (flat dict, single-key dicts, `nn.*`-scoped dicts, `"default"`
key) to canonical `QuantizerCfgEntry` lists. After normalization every
entry is guaranteed to have explicit `quantizer_name`, `enable`, and
`cfg` keys.
- Converted `_default_disabled_quantizer_cfg` and
`_mamba_moe_disabled_quantizer_cfg` from dicts to lists of
`QuantizerCfgEntry`.
- Added `_base_disable_all` (line 205): canonical deny-all entry
(`[{"quantizer_name": "*", "enable": False}]`).
- Converted all ~30 built-in config constants (`INT8_DEFAULT_CFG`,
`FP8_DEFAULT_CFG`, `NVFP4_DEFAULT_CFG`, etc.) to list format using
`*_base_disable_all` and `*_default_disabled_quantizer_cfg` unpacking.
- KV-cache configs (`FP8_KV_CFG`, `NVFP4_KV_CFG`, etc.) are now minimal
lists designed to be concatenated with a primary config — they
intentionally omit `_base_disable_all` and `"algorithm"`.
- Added two `QuantizeConfig` Pydantic field validators: a
`mode="before"` validator that calls `normalize_quant_cfg_list()`, and a
`mode="after"` validator that validates `cfg` dicts against
`QuantizerAttributeConfig`.
- Updated `need_calibration()` to iterate the normalized list instead of
the old dict.
- Changed `QuantizeQuantCfgType` alias from `dict[str | Callable, ...]`
to `list[QuantizerCfgEntry]`.

- **`conversion.py`**:
- Rewrote `set_quantizer_by_cfg()` (line 217) to iterate the list
directly. Each entry's `parent_class` is resolved via
`QuantModuleRegistry[parent_class_name]` (the existing `_DMRegistryCls`
registry).
- Added `set_quantizer_attributes_full()` (line 314): full replacement
of quantizer attributes from a `QuantizerAttributeConfig`. Unspecified
fields revert to defaults, enforcing entry atomicity. Can also upgrade
`TensorQuantizer` → `SequentialQuantizer` or downgrade the reverse.
- Added `set_quantizer_attributes_partial()` (line 384): merges a
partial `dict` of attributes into existing quantizer state. Does NOT
change quantizer structure. Used for enable-only entries.
- Added `set_quantizer_by_cfg_context()` context manager (line 447) that
temporarily applies a `quant_cfg` list and restores original quantizer
state on exit.
- Deprecated `set_quantizer_attribute()` (line 525) with a
`DeprecationWarning` pointing to the new functions.

- **`tensor_quantizer.py`**:
- `TensorQuantizer.set_from_attribute_config()`: narrowed type hint from
`dict` to `dict[str, Any]`.
- Added `_axis_setter` and `_block_sizes_setter` custom setters so that
`axis` and `block_sizes` changes properly propagate to the calibrator
and maintain mutual exclusivity.
- `SequentialQuantizer.set_from_attribute_config()`: narrowed signature
to `list[QuantizerAttributeConfig] | list[dict[str, Any]]` (removed the
old union with single values).

- **`algorithms.py`**:
- Updated `_match_quantizer_cfg()` to iterate the list and return
`(matched_cfg, matched_enable)` tuple with last-match-wins.
- Updated `_cfg_to_dict()`, `estimate_quant_compression()`, and
`QuantRecipe` to work with the list-based format.
- Updated `get_auto_quantize_config()` to emit list-format `quant_cfg`.

- **`model_quant.py`**: `disable_quantizer()` / `enable_quantizer()` now
call `set_quantizer_attributes_partial()` directly instead of the
deprecated `set_quantizer_attribute()`. Updated docstrings and code
examples to show the list format.

- **`utils/core_utils.py`**: `disable_lora_quantizers_in_config()` and
`update_quant_cfg_with_kv_cache_quant()` updated to append
`QuantizerCfgEntry` dicts to the list.

- **Other**: minor updates to `backends/fp8_per_tensor_gemm.py`,
`backends/nvfp4_gemm.py`, `compress.py`, `model_calib.py`,
`export/unified_export_hf.py`, and
`sparsity/attention_sparsity/conversion.py` to use the list format.

- **`onnx/llm_export_utils/quantization_utils.py`**: Updated
quantization config construction to use list format.

**YAML recipes (`modelopt_recipes/`)**

- Converted all 5 general PTQ recipes to the new list format:
  - `general/ptq/fp8_default-fp8_kv.yml`
  - `general/ptq/nvfp4_default-fp8_kv.yml`
  - `general/ptq/nvfp4_experts_only-fp8_kv.yml`
  - `general/ptq/nvfp4_mlp_only-fp8_kv.yml`
  - `general/ptq/nvfp4_omlp_only-fp8_kv.yml`
- Converted model-specific recipe:
`models/Step3.5-Flash/nvfp4-mlp-only.yaml`

**Documentation (`docs/`)**

- New guide: `docs/source/guides/_quant_cfg.rst` — comprehensive
reference covering entry format, ordering semantics, entry atomicity,
`enable` vs `cfg` independence, `parent_class` filtering, and common
patterns (deny-all-then-enable, customizing a built-in config, building
from scratch).
- Updated `_pytorch_quantization.rst` code examples to show the list
format with `copy.deepcopy` and `.append()`.
- Added `_quant_cfg.rst` to the quantization guide table of contents.

**Examples**

- Updated all quantization examples to use the list format:
`deepseek/ptq.py`, `diffusers/quantization/config.py`,
`llm_ptq/hf_ptq.py`, `llm_qat/main.py`, `vllm_serve/vllm_ptq_utils.py`,
`llm_autodeploy/run_auto_quantize.py`, `llm_eval/quantization_utils.py`,
`llm_ptq/example_utils.py`,
`windows/torch_onnx/diffusers/qad_example/sample_example_qad_diffusers.py`,
and 2 notebooks.

**Tests**

- New test file:
`tests/unit/torch/quantization/test_config_validation.py` — unit tests
for `need_calibration()`, `normalize_quant_cfg_list()` (new format,
legacy format conversions, error cases),
`find_quant_cfg_entry_by_path()`, `_match_quantizer_cfg()`, and
`QuantizeConfig` Pydantic validators.
- Extended `tests/unit/torch/quantization/test_quantize_cpu.py` with
tests for `set_quantizer_attributes_full()` (atomicity, parent_class
filtering, SequentialQuantizer creation), list ordering, enable-only
entry behavior, and end-to-end legacy dict format.
- Updated 20+ existing test files across `tests/unit/`, `tests/gpu/`,
`tests/gpu_megatron/`, and `tests/_test_utils/` to use the list format.

##### Backward compatibility

`normalize_quant_cfg_list()` is called automatically by the
`QuantizeConfig` Pydantic `mode="before"` validator, so existing code
passing the old dict-based format (flat dict like `{"*weight_quantizer":
{"num_bits": 8}}`, single-key dict lists, or `nn.*`-scoped dicts with
`parent_class` semantics) continues to work without modification. The
legacy `"default"` key is converted to `quantizer_name: "*"`.

`set_quantizer_attribute()` is preserved as a deprecated wrapper around
`set_quantizer_attributes_partial()`.

#### Test coverage

- **Unit tests**: new `test_config_validation.py` with tests for
normalization, validation, path lookup, and cfg matching. Extended
`test_quantize_cpu.py` with tests for full/partial attribute setting,
ordering, atomicity, and legacy backward compatibility.
- **System testing**:

```
python examples/llm_ptq/hf_ptq.py \
      --model Qwen/Qwen3-8B  \
      --recipe general/ptq/fp8_default-fp8_kv \
      --export_path=build/fp8_default-fp8_kv42  \
      --calib_size=16 \
      --batch_size=0 \
      --trust_remote_code \
      --export_fmt=hf
```

### Additional Information
<!-- E.g. related issue. -->

---------

Signed-off-by: Shengliang Xu <shengliangx@nvidia.com>
2026-04-06 15:38:44 -07:00
..

NVIDIA Model Optimizer - Windows

A Library to Quantize and Compress Deep Learning Models for Optimized Inference on Native Windows RTX GPUs

Documentation version license

Examples | Benchmark Results

Latest News

Table of Contents

Overview

The Model Optimizer - Windows (ModelOpt-Windows) is engineered to deliver advanced model compression techniques, including quantization, to Windows RTX PC systems. Specifically tailored to meet the needs of Windows users, ModelOpt-Windows is optimized for rapid and efficient quantization, featuring local GPU calibration, reduced system and video memory consumption, and swift processing times. The primary objective of the ModelOpt-Windows is to generate optimized, standards-compliant ONNX-format models. This makes it an ideal solution for seamless integration with ONNX Runtime (ORT) and DirectML (DML) frameworks, ensuring broad compatibility with any inference framework supporting the ONNX standard. Furthermore, ModelOpt-Windows integrates smoothly within the Windows ecosystem, with full support for tools and SDKs such as Olive and ONNX Runtime, enabling deployment of quantized models across various independent hardware vendors (IHVs) through the DML path and TensorRT path.

Model Optimizer is available for free for all developers on NVIDIA PyPI. This repository is for sharing examples and GPU-optimized recipes as well as collecting feedback from the community.

Installation

ModelOpt-Windows can be installed either as a standalone toolkit or through Microsoft's Olive.

Standalone Toolkit Installation (with CUDA 12.x)

To install ModelOpt-Windows as a standalone toolkit on CUDA 12.x systems, run the following commands:

pip install nvidia-modelopt[onnx]

Installation with Olive

The ModelOpt-Windows is integrated into Microsoft's Olive framework. Run the following commands to install ModelOpt through Olive.

pip install olive-ai[nvmo]
pip install onnxruntime-genai-cuda

For more details, or to use different ONNX Runtime Execution Providers, refer to the detailed installation instructions.

Techniques

Quantization

Quantization is an effective model optimization technique for large models. Quantization with ModelOpt-Windows can compress model size by 2x-4x, speeding up inference while preserving model quality. ModelOpt-Window enables highly performant quantization formats including INT4, FP8, INT8, etc. and supports advanced algorithms such as AWQ and SmoothQuant* focusing on post-training quantization (PTQ) for ONNX and PyTorch* models with DirectML, CUDA and TensorRT* inference backends.

For more details, please refer to the detailed quantization guide.

Getting Started

The ONNX quantization API requires a model, calibration data, along with quantization settings like algorithm, calibration-EPs etc. Here’s an example snippet to apply INT4 AWQ quantization:

from modelopt.onnx.quantization.int4 import quantize as quantize_int4
# import other packages as needed
calib_inputs = get_calib_inputs(dataset, model_name, cache_dir, calib_size, batch_size,...)
quantized_onnx_model = quantize_int4(
    onnx_path,
    calibration_method="awq_lite",
    calibration_data_reader=None if use_random_calib else calib_inputs,
    calibration_eps=["dml", "cpu"]
)
onnx.save_model(
    quantized_onnx_model,
    output_path,
    save_as_external_data=True,
    location=os.path.basename(output_path) + "_data",
    size_threshold=0,
)

Check modelopt.onnx.quantization.quantize_int4 for details about INT4 quantization API.

Refer to our Support Matrix for details about supported features and models.

To learn more about ONNX PTQ, refer to our docs.

Deployment

The quantized onnx model can be deployed using frameworks like onnxruntime. Ensure that model’s opset is 19+ for FP8 quantization, and it is 21+ for INT4 quantization. This is needed due to different opset requirements of ONNX’s Q/DQ nodes for INT4, FP8 data-types support. Refer to Apply Post Training Quantization (PTQ) for details.

# write steps (say, upgrade_opset() method) to upgrade or patch opset of the model, if needed
# the opset-upgrade, if needed, can be done on either base ONNX model or on the quantized model
# finally, save the quantized model

quantized_onnx_model = upgrade_opset(quantized_onnx_model)
onnx.save_model(
    quantized_onnx_model,
    output_path,
    save_as_external_data=True,
    location=os.path.basename(output_path) + "_data",
    size_threshold=0,
)

For detailed instructions about deployment of quantized models with ONNX Runtime, see the ONNX Runtime Deployment Guide.

Note

The ready-to-deploy optimized ONNX models from ModelOpt-Windows are available at HuggingFace NVIDIA collections.

Examples

  • Examples for Post-Training Quantization (PTQ) of ONNX models:
    • PTQ for GenAI LLMs covers how to use ONNX PTQ with ONNX Runtime GenAI built LLM ONNX models, and their deployment with DirectML.
    • PTQ for Whisper illustrates using ONNX PTQ with a Whisper ONNX model (i.e. an ASR model). It also provides example script for Optimum-ORT based inference of Whisper using CUDA EP.
    • PTQ for SAM2 illustrates using ONNX PTQ with a SAM2 ONNX model (i.e. a segmentation model).
  • Examples that demonstrate PTQ of a PyTorch model followed by ONNX export:
    • Diffusers example demonstrates how to apply PTQ to diffusion models in PyTorch format and then export the quantized models to ONNX.
  • MMLU Benchmark provides an example script for MMLU benchmarking of LLM models, and demonstrates how to run it with various popular backends like DirectML, TensorRT-LLM* and model formats like ONNX and PyTorch*.

Support Matrix

Model Type Support Matrix
Large Language Models (LLMs) View Support Matrix
Automatic Speech Recognition View Support Matrix
Segmentation Models View Support Matrix
Diffusion Models View Support Matrix

Benchmark Results

Please refer to benchmark results for performance and accuracy comparisons of popular Large Language Models (LLMs).

Collection Of Optimized ONNX Models

The ready-to-deploy optimized ONNX models from ModelOpt-Windows are available at HuggingFace NVIDIA collections. These models can be deployed using DirectML backend. Follow the instructions provided along with the published models for deployment.

Release Notes

Please refer to changelog

* Experimental support