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@bnellnm bnellnm commented Jul 2, 2025

This import was breaking on TPU. Only import CutlassExpertsFp8 in the function where it is used.

cc @tlrmchlsmth , @WoosukKwon , @varun-sundar-rabindranath

Signed-off-by: Bill Nell <bnell@redhat.com>
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Summary of Changes

Hello @bnellnm, 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 implements a targeted bugfix to enhance compatibility with TPU environments by adjusting how a specific dependency is imported. The core change involves moving an import statement from a global scope to a local function scope, which resolves a reported breakage and optimizes the module's loading behavior.

Highlights

  • Bugfix: TPU Compatibility: I've addressed a bug where importing CutlassExpertsFp8 globally caused issues on TPU environments. The import has been moved to the specific function (select_gemm_impl) where it is actually utilized, ensuring it's only loaded when needed and resolving the TPU-related breakage.
  • Import Optimization: The change refactors the import statement for CutlassExpertsFp8 from a module-level import to a function-local import. This improves module load time and avoids potential conflicts or errors in environments where the imported module might not be available or compatible at the global scope.
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Code Review

This pull request addresses a bug where a top-level import of CutlassExpertsFp8 was causing issues on TPU platforms. The fix is to move this import to be local within the select_gemm_impl function, where it is used. This is a standard and effective way to handle platform-specific dependencies that might not be available everywhere. The change is correct, well-contained, and directly solves the stated problem. I have reviewed the changes and found no issues of medium or higher severity. The code quality is good.

@tlrmchlsmth tlrmchlsmth added the ready ONLY add when PR is ready to merge/full CI is needed label Jul 2, 2025
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@aarnphm aarnphm enabled auto-merge (squash) July 2, 2025 16:46
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did a test,

the error changed from ImportError: cannot import name 'CutlassExpertsFp8' from 'vllm.model_executor.layers.fused_moe' (/workspace/vllm/vllm/model_executor/layers/fused_moe/__init__.py) to ImportError: cannot import name 'fused_experts' from 'vllm.model_executor.layers.fused_moe' (/workspace/vllm/vllm/model_executor/layers/fused_moe/__init__.py)

Signed-off-by: Bill Nell <bnell@redhat.com>
auto-merge was automatically disabled July 2, 2025 17:20

Head branch was pushed to by a user without write access

@QiliangCui
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now, it is

ImportError: cannot import name 'BatchedTritonOrDeepGemmExperts' from 'vllm.model_executor.layers.fused_moe' (/workspace/vllm/vllm/model_executor/layers/fused_moe/__init__.py)

Signed-off-by: Bill Nell <bnell@redhat.com>
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tested and it runs for me now. thank you!

@bnellnm
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bnellnm commented Jul 2, 2025

tested and it runs for me now. thank you!

Thanks for verifying the fix!

@tlrmchlsmth tlrmchlsmth enabled auto-merge (squash) July 2, 2025 22:23
@mgoin mgoin mentioned this pull request Jul 3, 2025
@tlrmchlsmth tlrmchlsmth merged commit 2e25bb1 into vllm-project:main Jul 3, 2025
77 checks passed
sfeng33 pushed a commit to sfeng33/vllm that referenced this pull request Jul 6, 2025
huydhn pushed a commit to huydhn/vllm that referenced this pull request Jul 8, 2025
LyrisZhong pushed a commit to LyrisZhong/vllm that referenced this pull request Jul 23, 2025
avigny pushed a commit to avigny/vllm that referenced this pull request Jul 31, 2025
…vllm-project#20381)

Signed-off-by: Bill Nell <bnell@redhat.com>
Signed-off-by: avigny <47987522+avigny@users.noreply.github.com>
Pradyun92 pushed a commit to Pradyun92/vllm that referenced this pull request Aug 6, 2025
jinzhen-lin pushed a commit to jinzhen-lin/vllm that referenced this pull request Aug 9, 2025
…vllm-project#20381)

Signed-off-by: Bill Nell <bnell@redhat.com>
Signed-off-by: Jinzhen Lin <linjinzhen@hotmail.com>
googlercolin pushed a commit to googlercolin/vllm that referenced this pull request Aug 29, 2025
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