[Feature] add procese set cpu affinity current gpu device

[lengrongfu]

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)". [Feature]: Pin vLLM process to the right NUMA Region #13855
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

Purpose

Test Plan

Test Result

(Optional) Documentation Update

[github-actions]

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[gemini-code-assist]

Code Review

This pull request introduces a feature to set CPU affinity for worker processes based on the GPU they are assigned to, which can improve performance in NUMA architectures. The implementation adds a set_cpu_affinity method to NvmlCudaPlatform and calls it during worker initialization. My review identifies a critical issue where the program could crash if NVML is not available, as the corresponding platform class is missing the new method. I've provided a fix for this.

[lengrongfu]

@WoosukKwon Can you help review this pr? thanks ~