Revert "[MXFP4] Support for linear layers + compressed-tensors integration" (#41664)#42473
Revert "[MXFP4] Support for linear layers + compressed-tensors integration" (#41664)#42473vllm-agent wants to merge 1 commit into
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…ation (vllm-project#41664)" This reverts commit a7b801e.
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Code Review
This pull request removes the generic MXFP4 linear kernel infrastructure and the W4A4 MXFP4 scheme, replacing it with a W4A16 weight-only scheme that utilizes Marlin directly. It also refactors FlashInfer utilities by removing MXFP4-specific quantization functions and simplifying the flashinfer_scaled_fp4_mm interface. Feedback highlights that making the alpha parameter mandatory in flashinfer_scaled_fp4_mm may break existing callers and suggests clarifying the weight registration process when transitioning from packed weights.
| block_scale_a: torch.Tensor, | ||
| block_scale_b: torch.Tensor, | ||
| alpha: torch.Tensor | None, | ||
| alpha: torch.Tensor, |
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The alpha parameter is now a required argument, whereas it was previously optional (defaulting to None and then to a tensor of ones). This change could break existing callers of flashinfer_scaled_fp4_mm or flashinfer_scaled_fp4_mm_out that do not provide this argument, especially for non-MXFP4 paths (like NVFP4) that might have relied on the default behavior. If this is a revert, please ensure that all callers in the codebase have been updated to provide this tensor, or restore the optional behavior with a default value.
| layer.weight = Parameter(layer.weight_packed.data, requires_grad=False) | ||
| del layer.weight_packed |
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While reassigning layer.weight and deleting layer.weight_packed works for the Marlin kernel, it's important to note that layer.weight is a standard attribute name for linear layers. If this module is part of a larger fused structure or if other utilities expect weight_packed to exist during the loading phase, this deletion might cause issues. However, since this is typically the final step after loading, it should be safe as long as no subsequent hooks rely on the original parameter name.
| layer.weight = Parameter(layer.weight_packed.data, requires_grad=False) | |
| del layer.weight_packed | |
| # Ensure weight is registered as a parameter for the module | |
| layer.weight = Parameter(layer.weight_packed.data, requires_grad=False) | |
| del layer.weight_packed |
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Revert of #41664
This reverts the merge commit a7b801e from PR #41664.
Reason: This PR is linked to 1 new CI failure in build #65912:
gpt-oss-20b-sm100-fi-mxfp4-mxfp8-trtllmeval config timed out after 1800s on B200, processing only ~12/1584 items. The MXFP4 kernel and compressed-tensors changes in this PR directly affect the failing codepath. Two other MXFP4 configs (flashinfer-mxfp4-bf16, flashinfer-mxfp4-mxfp8-cutlass) passed, but the SM100/TRT-LLM variant experienced a severe performance regression.