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@fzyzcjy fzyzcjy commented Jun 13, 2025

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Summary of Changes

Hello @fzyzcjy, 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 is the first part of an effort to remove a performance bottleneck identified as a slow concatenation operation within the CUTLASS MLA kernel. It refactors the kernel and its surrounding code to accept the query tensor split into its non-positional (q_nope) and positional (q_pe) components upfront, eliminating the need for concatenation inside the kernel.

Highlights

  • Kernel Signature Change: The cutlass_mla_decode kernel and its interfaces (Python wrapper, C++ binding, header) have been updated to accept two separate query tensors (q_nope and q_pe) instead of a single concatenated q_nope_and_q_pe tensor.
  • Benchmark and Test Updates: The benchmark script (bench_cutlass_mla.py) and the test script (test_cutlass_mla.py) have been modified to generate and pass the split query tensors (q_nope, q_pe) to the updated cutlass_mla_decode function.
  • CUDA Version Check Removed: The conditional compilation block checking for CUDA version >= 12.4 in cutlass_mla_kernel.cu has been commented out, effectively making the kernel always available.
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@fzyzcjy fzyzcjy closed this Jun 13, 2025
@fzyzcjy fzyzcjy force-pushed the feat/mla_cat_sgl_kernel branch from 831fc43 to 2f4ec75 Compare June 13, 2025 08:42
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Code Review

The pull request refactors the cutlass_mla_decode function to accept separate q_nope and q_pe tensors, enhancing code modularity and potentially improving performance. The changes are consistently applied across the codebase, including benchmarks and tests. Key areas for review include ensuring type consistency, optimizing tensor creation, and clarifying device initialization.

@fzyzcjy fzyzcjy reopened this Jun 13, 2025
@fzyzcjy fzyzcjy marked this pull request as ready for review June 13, 2025 08:43
@zhyncs zhyncs merged commit aa46ed3 into sgl-project:main Jun 13, 2025
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