[NV] Update: sglang v2 Qwen3.5 h200 MTP

[hshrivastava-droid]

Summary

Enable SGLang speculative decoding v2 (SGLANG_ENABLE_SPEC_V2=1) for the Qwen3.5 FP8 H200 MTP benchmark configuration.

Changes

• benchmarks/single_node/qwen3.5_fp8_h200_mtp.sh: Set SGLANG_ENABLE_SPEC_V2=1 environment variable on the sglang.launch_server command to enable the v2 speculative decoding engine for EAGLE-based multi-token prediction
• perf-changelog.yaml: Added changelog entry for qwen3.5-fp8-h200-sglang-mtp documenting the spec v2 enablement

Context

The Qwen3.5 FP8 H200 MTP benchmark uses EAGLE speculative decoding (3 speculative steps, 4 draft tokens, topk=1). This PR enables SGLang's v2 speculative decoding implementation via the SGLANG_ENABLE_SPEC_V2=1 flag, which is expected to improve MTP performance.

[github-actions]

Thanks for the contribution! For vLLM & SGLang, please ensure that your recipes is similar to the official vLLM recipes and/or the SGLang cookbook

• https://cookbook.sglang.io/
• https://docs.vllm.ai/projects/recipes/en/latest/

If it is not, please create a PR first before we can merge your PR into the master branch. Let's ensure that the documentation is first class such that the entire ML community can benefit from your hard work! Thank you

• https://github.com/vllm-project/recipes
• https://github.com/sgl-project/sgl-cookbook

[hshrivastava-droid]

@claude add PR description

[Klaud-Cold]

Claude finished @hshrivastava-droid's task in 38s —— View job

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Adding PR Description

• Gather context from changed files and diff
• Write and update PR description

PR description has been added. It covers:

• Summary: Enabling SGLang speculative decoding v2 for the Qwen3.5 FP8 H200 MTP benchmark
• Changes: The two modified files and what each change does
• Context: Background on the EAGLE speculative decoding config and the purpose of the SGLANG_ENABLE_SPEC_V2=1 flag

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[jgangani]

LGTM

[functionstackx]

cookbook plz 😭

[hshrivastava-droid]

Sglang cookbook- sgl-project/sgl-cookbook#240

[hshrivastava-droid]

@functionstackx - could you please review this?

[Oseltamivir]

lgtm