[Kernel] correct cpu worker function parameter type

[andyxning]

Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
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Purpose

The type hints for src_to_dst and src_to_dsts should be torch.Tensor.

Test Plan

NA

Test Result

NA

(Optional) Documentation Update

[github-actions]

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[gemini-code-assist]

Summary of Changes

Hello @andyxning, 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 primarily focuses on enhancing code clarity and correctness by refining type hints for parameters in CPU worker functions, ensuring they accurately reflect the use of torch.Tensor objects for cache operations. A small stylistic cleanup was also included.

Highlights

• Type Hint Refinement: Updated the type hints for src_to_dst and src_to_dsts parameters in the swap_in, swap_out, and copy methods within vllm/worker/cpu_worker.py from dictionary types to torch.Tensor. This clarifies the expected input type for these cache operation functions.
• Minor Code Style Improvement: Removed redundant parentheses from a tuple return statement in the get_kv_cache_shape static method within vllm/attention/ops/ipex_attn.py, improving code readability.

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[gemini-code-assist]

Code Review

This pull request updates the type hints for src_to_dst in swap_in/swap_out methods and src_to_dsts in the copy method of CPUCacheEngine to torch.Tensor. These changes align the method signatures with their intended usage, the WorkerInput data structures, and the underlying attention backend interfaces (specifically IPEXAttnBackend). This enhances code clarity, maintainability, and type consistency.

[gemini-code-assist]

Changing the type hint for src_to_dst from Dict[int, int] to torch.Tensor improves type consistency with the blocks_to_swap_in field in the WorkerInput dataclass and the swap_blocks method in the IPEXAttnBackend.

src_to_dst: torch.Tensor

[gemini-code-assist]

Updating the type hint for src_to_dst to torch.Tensor improves type consistency with the blocks_to_swap_out field in WorkerInput and the IPEXAttnBackend.swap_blocks method signature.

src_to_dst: torch.Tensor

[gemini-code-assist]

Changing the type hint for src_to_dsts from Dict[int, List[int]] to torch.Tensor improves type consistency with the blocks_to_copy which is a torch.Tensor in CPUWorker.prepare_worker_input and with the IPEXAttnBackend.copy_blocks method, which expects src_to_dists: torch.Tensor.

src_to_dsts: torch.Tensor

[mgoin]

LGTM, thanks!