Chenjie LuoandClaude Opus 5 b16356776b Build the GGML IQ packing kernels as a single CUDA extension (#2462)
### What does this PR do?

Type of change: Code refactoring

`#2448` added the GGML IQ packing kernels as **two** torch extensions,
`modelopt_cuda_ext_iq1_s` and `modelopt_cuda_ext_iq2_xs`. This merges
them into one,
`modelopt_cuda_ext_ggml`.

The existing per-extension split in `extensions.py` exists for reasons
that don't apply
to the IQ formats: `get_cuda_ext` gates on CUDA `>=11` while
`_fp8`/`_mx` gate on
`>=11.8`, and `_mx` needs `--use_fast_math`, which must not reach the
base `tensor_quant`
kernels. `get_cuda_ext_iq1_s` and `get_cuda_ext_iq2_xs` differed in none
of that —
same `>=11.8` gate, same `-O3` flags, same `common.cuh` — so the split
only compiled the
shared header twice, ran nvcc twice, and grew the loader, `__getattr__`,
and
`precompile()` once per format. With IQ2_XXS / IQ3_S / IQ4_NL plausibly
following, that
scales badly.

Changes:

- New `ggml/ggml.cpp` holds both host-side validation wrappers and the
single
`PYBIND11_MODULE`, binding `iq1_s_pack` and `iq2_xs_pack` (previously
each module
exported a bare `pack`). Deletes `ggml/iq1_s.cpp` and `ggml/iq2_xs.cpp`;
the
  validation logic and docstrings carry over unchanged.
- `get_cuda_ext_iq1_s` + `get_cuda_ext_iq2_xs` → `get_cuda_ext_ggml`,
which builds
`ggml.cpp`, `iq1_s.cu`, and `iq2_xs.cu` together. The
retry-on-`raise_if_failed`
  semantics of the old getters are preserved.
- Each format keeps its kernels in its own translation unit, so adding a
format is a new
`.cu` plus one `module.def` — no new extension, loader, or
`precompile()` line.

No caller outside `extensions.py` and its tests referenced the old
getters on `main`, so
nothing else changes. **Note for the follow-up PRs in the `#2448` series
(`#2446`/`#2447`/`#2449`): the codec layer should call
`get_cuda_ext_ggml().iq1_s_pack(...)` / `.iq2_xs_pack(...)` instead of
`get_cuda_ext_iq1_s().pack(...)` / `get_cuda_ext_iq2_xs().pack(...)`.**

### Usage

```python
from modelopt.torch.quantization.extensions import get_cuda_ext_ggml

ext = get_cuda_ext_ggml(raise_if_failed=True)
iq1_s_payload = ext.iq1_s_pack(weight, iq1s_grid)            # uint8 [numel / 256, 50]
iq2_xs_payload = ext.iq2_xs_pack(weight, iq2xs_grid, scales) # uint8 [numel / 256, 74]
```

### Testing

Ran on a single H200 NVL (TRT-LLM `1.3.0rc27.dev202609170000`
container), building the
merged extension from scratch:

- `pytest tests/gpu/_extensions/test_torch_extensions.py` — **24
passed** (6:44). This
is the full existing IQ suite (zero-block layout, encode, dtype
rejection,
row-straddling rejection, invalid/negative-zero scales, byte-exact dtype
equivalence,
and the brute-force optimality round-trip) reparametrized onto the
merged module,
  plus the untouched `modelopt_cuda_ext` / `_fp8` / `_mx` load tests.
- Verified `precompile()` loads all four extensions and that the merged
module exports
  exactly `iq1_s_pack` and `iq2_xs_pack` with the expected arities.
- Off-GPU: compiled the three sources directly and linked them into one
`.so` to confirm
no duplicate-symbol collisions between the two `.cu` translation units.
- `pre-commit run --files ...` passes on all changed files (ruff, mypy,
clang-format,
  bandit, license headers).

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

- Is this change backward compatible?: ✅ — the removed getters were
added in `#2448`
(merged today, unreleased) and have no callers outside this file's own
tests.
- If you copied code from any other sources or added a new PIP
dependency, did you follow guidance in `CONTRIBUTING.md`: N/A — no new
code or dependencies; the moved wrappers keep their original
attribution.
- Did you write any new necessary tests?: ✅ — existing coverage
reparametrized onto the merged module; no behavior change to test.
- Did you update
[Changelog](https://github.com/NVIDIA/Model-Optimizer/blob/main/CHANGELOG.rst)?:
N/A — internal refactor of an unreleased, not-yet-wired-up API.
- Did you get Claude approval on this PR?: ❌ — not yet run.

### Additional Information

Follow-up to #2448. Merge before the remaining PRs in that series
(#2446, #2447, #2449)
land, so the codec layer is written against `get_cuda_ext_ggml` and no
rename is needed
afterwards.

🤖 Generated with [Claude Code](https://claude.com/claude-code)


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

## Summary by CodeRabbit

- **New Features**
  - Added IQ1_S packing support through the GGML CUDA extension.
  - Added a unified GGML extension loader for IQ1_S and IQ2_XS packing.
- Improved extension loading reliability when a cached extension is
unavailable.

- **Changes**
  - Renamed the IQ2_XS packing binding from `pack` to `iq2_xs_pack`.
- Consolidated IQ1_S and IQ2_XS extension access under the shared GGML
loader.
- Updated GPU validation and coverage to use the unified extension
interface.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Signed-off-by: Chenjie Luo <chenjiel@nvidia.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-17 20:46:41 +00:00
2026-09-17 20:08:12 +00:00
…
…
…

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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.

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cd Model-Optimizer

pip install -e .[dev]

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

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Techniques

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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]

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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}
}

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