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Fix bias handling in TritonMoeQuantInfo within quantization/mxfp4.py#10579

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zhyncs merged 2 commits intosgl-project:mainfrom
yhyang201:bug-fix
Sep 18, 2025
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Fix bias handling in TritonMoeQuantInfo within quantization/mxfp4.py#10579
zhyncs merged 2 commits intosgl-project:mainfrom
yhyang201:bug-fix

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Motivation

This PR fixes a field mismatch when constructing TritonMoeQuantInfo in quantization/mxfp4.py.

  • Issue: The call site passed w13_weight_bias and w2_weight_bias, but TritonMoeQuantInfo defines these as optional fields b13 and b2. This could raise a TypeError and/or leave biases unwired.
  • Fix: Pass biases via b13 and b2, sourcing them from the layer with getattr(..., None) to safely handle layers without bias parameters.
  • Impact: Prevents constructor errors and correctly wires optional biases in the MoE quantization path. No behavioral change when biases are absent; scope limited to quantization/mxfp4.py.

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Accuracy Tests

Benchmarking and Profiling

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Summary of Changes

Hello @yhyang201, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical field mismatch in the TritonMoeQuantInfo constructor within the MoE quantization module. By refactoring how optional bias parameters are accessed and passed, the change ensures that the system robustly handles layers both with and without bias attributes, preventing runtime errors and maintaining the integrity of the quantization process without altering existing behavior for cases where biases are absent.

Highlights

  • Bias Parameter Handling: Corrected a field mismatch when constructing TritonMoeQuantInfo by changing how w13_weight_bias and w2_weight_bias are passed.
  • Error Prevention: The fix now uses getattr(layer, "attribute_name", None) to safely retrieve bias parameters, preventing potential TypeError exceptions if the bias attributes are not present on the layer object.
  • Parameter Mapping: The w13_weight_bias and w2_weight_bias parameters are now correctly mapped to the b13 and b2 fields of TritonMoeQuantInfo respectively, ensuring proper wiring of optional biases in the MoE quantization path.
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Code Review

This pull request addresses a bug in quantization/mxfp4.py by correcting the keyword arguments used to instantiate TritonMoeQuantInfo. The change replaces the incorrect w13_weight_bias and w2_weight_bias with the expected b13 and b2 parameters. Furthermore, the use of getattr with a default None value is a robust way to handle optional bias attributes, preventing potential errors and ensuring that biases are correctly passed when present. The fix is correct, well-contained, and improves the reliability of the MoE quantization path.

@ch-wan ch-wan self-assigned this Sep 17, 2025
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LGTM

@ch-wan ch-wan added the ready-to-merge The PR is ready to merge after the CI is green. label Sep 17, 2025
@zhyncs zhyncs merged commit 388c05d into sgl-project:main Sep 18, 2025
7 of 56 checks passed
chenxu140 added a commit to ping1jing2/sglang that referenced this pull request Sep 20, 2025
* origin/qwen3: (30 commits)
  chore: bump sgl-kernel 0.3.11 (sgl-project#10630)
  feat: add fused moe config for Qwen3-Next-80B-A3B-Instruct on B200 (sgl-project#10631)
  model support: Sarashina2VisionForCausalLM (sgl-project#10632)
  [Performance] Qwen3-Next: speed up update_mamba_state_after_mtp_verify by 10x; e2e up to 3.54% faster (sgl-project#10586)
  [Performance] Qwen3-Next: replace arange to cached query_start_loc_li… (sgl-project#10553)
  [Feature] Speculative decoding support lookahead (sgl-project#9873)
  refactor: use registry for _get_attention_backend_from_str (sgl-project#10629)
  [router] refactor worker to builder pattern 1/n (sgl-project#10628)
  Garbage collector regression in the online server (sgl-project#10621)
  feat: Add FlexAttention Backend for Efficient Sparse Attention (sgl-project#9947)
  Fix bias handling in TritonMoeQuantInfo within quantization/mxfp4.py (sgl-project#10579)
  [Performance] qwen3-next improve causal conv1d in prefill phase (sgl-project#10595)
  Fix sgl_kernel import failure on devices other than CUDA (sgl-project#10610)
  support qwen3-next-fp8 deepep (sgl-project#10622)
  update deepep version for qwen3-next deepep moe (sgl-project#10624)
  Feat/add heartbeat mechanism for nixl conn (sgl-project#10222)
  [RL] Add destroy process group api (sgl-project#9979)
  fix deepep assert when PD disaggregation == null (sgl-project#8274)
  Scale kkt after reduction (sgl-project#10604)
  [improvement] add average input/output token length for hicache benchmark stats output (sgl-project#10525)
  ...
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4 participants