fix gpu out token counter update error

[hiworldwzj]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @hiworldwzj, 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 and fixes an error in the GPU-based output token counter update mechanism. It introduces a more robust and flexible way to update token counts on the GPU by allowing conditional updates via a mask, and integrates this improved counting logic throughout the inference pipeline to ensure accuracy.

Highlights

• GPU Token Counter Kernel Enhancement: The Triton kernel _token_id_counter_update_kernel has been updated to accept an optional mask_ptr and a HAS_MASK constexpr. This allows the atomic addition operation to be conditionally applied based on a per-element boolean mask, ensuring that only relevant tokens contribute to the counter, which is crucial for accurate counting in scenarios like speculative decoding.
• Refactored Token Counter Management: The ReqManager now includes a new dedicated method, update_reqs_out_token_counter_gpu, which specifically handles GPU-based output token counter updates by calling the enhanced Triton kernel. This change cleanly separates GPU-based counting logic from CPU-based counting, improving code organization and maintainability.
• Integration of Masked GPU Counting: The newly enhanced GPU token counter update mechanism, complete with masking support, has been integrated into various prefill and decode operations across different inference backends (e.g., chunked_prefill and dp_backend). This ensures that the GPU-side token counts are accurately maintained for all generated tokens, especially when only a subset of tokens (e.g., accepted tokens in speculative decoding) should be counted.

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[gemini-code-assist]

Code Review

This pull request fixes an issue with the GPU output token counter by adding the update logic in various model backends. The introduction of a mask for conditional updates is a good addition. The refactoring in req_manager.py improves code structure by separating GPU-specific logic. Overall, the changes are well-implemented and address the problem effectively. One suggestion improves code clarity and reduces duplication in the Triton kernel.

[gemini-code-assist]

To improve maintainability and reduce code duplication, this if/else block can be refactored. The tl.atomic_add call is repeated in both branches with only the mask parameter being different. Determine the mask to use first, and then make a single tl.atomic_add call.

    final_mask = loc_mask
    if HAS_MASK:
        mask = tl.load(mask_ptr + offs, mask=loc_mask, other=False)
        final_mask = final_mask & mask

    tl.atomic_add(
        req_to_out_token_id_counter_ptr + req_idx * counter_stride_m + token_ids * counter_stride_n,
        1,
        mask=final_mask,
    )