[Bugfix] Fix KDA output

[jeejeelee]

Purpose

Test Plan

local-completions (model=moonshotai/Kimi-Linear-48B-A3B-Instruct,base_url=http://0.0.0.0:8000/v1/completions,tokenized_requests=False,tokenizer_backend=None,num_concurrent=8), gen_kwargs: (None), limit: None, num_fewshot: 5, batch_size: 1
|Tasks|Version|     Filter     |n-shot|  Metric   |   |Value |   |Stderr|
|-----|------:|----------------|-----:|-----------|---|-----:|---|-----:|
|gsm8k|      3|flexible-extract|     5|exact_match|↑  |0.8908|±  |0.0086|
|     |       |strict-match    |     5|exact_match|↑  |0.8741|±  |0.0091|

Test Result

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
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[gemini-code-assist]

Code Review

This pull request addresses a bug in the output mechanism of the KimiDeltaAttention layer. The forward method's signature and implementation have been updated to write the result to a pre-allocated output tensor, rather than returning a new tensor. This change aligns the layer with vLLM's standard practice of using in-place operations for performance and compatibility with features like CUDA graphs. The modification is correct and resolves the bug by ensuring the layer conforms to the expected API.

[zhiyuan1i]

Thank you for your timely fix.

LGTM.

[youkaichao]

thanks for the fix!

[ZJY0516]

Thanks for catching that—my mistake.