Remove unused swap_space parameter

[mcelrath]

References: #27984

Purpose

Remove unused swap_space parameter after the removal of best_of sampling. Fixes #27984

Test Plan

(Untested) working on it.

Help would be appreciated. I'm having quite a lot of difficulty compiling vllm and all its dependencies. This should be a simple fix with no impact anywhere else.

Test Result

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[mergify]

Documentation preview: https://vllm--27988.org.readthedocs.build/en/27988/

[gemini-code-assist]

Code Review

This pull request aims to remove the unused swap_space parameter throughout the codebase. The changes are comprehensive, touching documentation, tests, and core configuration files. While most of the changes are correct, I've identified a critical issue in vllm/engine/arg_utils.py that appears to be a typo. This typo will likely cause a KeyError during command-line argument parsing, breaking the CLI. I've provided a suggestion to fix this.

[gemini-code-assist]

There seems to be a typo here. The get_kwargs(CacheConfig) function returns a dictionary with keys corresponding to the fields in CacheConfig. CacheConfig has a field named cache_dtype, but not kv_cache_dtype. Accessing cache_kwargs["kv_cache_dtype"] will likely cause a KeyError. This should probably be cache_kwargs["cache_dtype"] as it was before this change.

Suggested change

	cache_group.add_argument("--kv-cache-dtype", **cache_kwargs["kv_cache_dtype"])
	cache_group.add_argument("--kv-cache-dtype", **cache_kwargs["cache_dtype"])

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Fix CLI lookup for kv cache dtype option

The new code builds the CLI by fetching cache_kwargs["kv_cache_dtype"], but the CacheConfig dataclass still exposes the field as cache_dtype. get_kwargs(CacheConfig) therefore produces a dictionary with key "cache_dtype", and this lookup now raises a KeyError as soon as the argument parser is constructed (e.g. running python -m vllm.entrypoints.llm --help). This prevents the CLI from starting at all. Keep the lookup keyed on "cache_dtype" or rename the field consistently.

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[hmellor]

I see a few more references that aren't removed by this PR:

cc @ApostaC does LMCache depend on the swap_space argument at all in vllm/distributed/kv_transfer/kv_connector/v1/lmcache_integration/vllm_v1_adapter.py?

[ApostaC]

Hey @hmellor , we don't use that at all.