docs(vllm): refresh --benchmark-mode sweep description

[dagil-nvidia]

Summary

Originally this PR spliced the release/1.4.0 Benchmarking and Deprecated sections into main's vLLM configuration reference. #13036 merged the same content to main minutes earlier, so the branch has been merged up to main and the PR reduced to the one remaining gap, flagged by Devin review: the --benchmark-mode field still described the removed ISL / (context_length × batch_size) grid.

• Rewrites the --benchmark-mode description to match the shipped help text in DynamoVllmArgGroup: iteration-total prefill new-token / KV-read-token / batch-size axes and decode KV-read-token / batch-size axes, derived from the engine's own limits (components/src/dynamo/vllm/backend_args.py:242-250).
• CodeRabbit's finding on the points-file wording was verified against the code and refuted (see the resolved thread): with --benchmark-points-file set, args.py never forwards the CLI sampling limits into additional_config["benchmark"], so the scheduler validates only its own defaults — "ignored" is accurate.

Validation

• Net diff vs main is the single --benchmark-mode paragraph; git diff origin/main...HEAD shows 1 file, 1 line.
• ForwardPassMetrics confirmed still current (10 references in instrumented_scheduler.py).
• pre-commit run --files docs/fern/pages/reference/backends/vllm-configuration.mdx passes.

🤖 Generated with Claude Code

[dagil-nvidia]

/ok to test e19f29a

[devin-ai-integration]

Devin Review found 1 potential issue.

[coderabbitai]

Walkthrough

Changes

vLLM benchmark configuration

Layer / File(s)	Summary
Benchmark sampling and timeout options docs/fern/pages/reference/backends/vllm-configuration.mdx	Documents explicit benchmark point files, phase-specific sampling limits, and the 900-second timeout behavior.
Legacy granularity compatibility docs/fern/pages/reference/backends/vllm-configuration.mdx	Documents deprecated granularity mappings, validation, conflict detection, and suppression conditions.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🔵 Low · up to e19f2

The change documents the shipped benchmarking flags, but one statement could mislead users into configuring invalid sampling limits that cause command parsing to fail when a points file is used. The PR is otherwise mergeable with this documentation correction explicitly addressed.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the change and validation, but it omits the required template sections and issue-linkage confirmation.	Use the required headings and complete Related Issues by linking an issue or confirming that no related issue exists.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title accurately identifies the benchmark-mode documentation change, which matches the stated remaining scope.

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[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@docs/fern/pages/reference/backends/vllm-configuration.mdx`:
- Around line 194-195: Update the --benchmark-points-file description to clarify
that sampling limits do not generate points when an explicit file is provided,
but all five limits are still validated and must be valid. Preserve the existing
behavior unless instrumented_scheduler.py is intentionally changed to skip
validation.

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Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

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📥 Commits

Reviewing files that changed from the base of the PR and between beb7629 and e19f29a.

📒 Files selected for processing (1)

• docs/fern/pages/reference/backends/vllm-configuration.mdx

[github-actions]

🌿 Fern Docs Preview: https://nvidia-preview-01a001dc-1cdd-7753-8714-90a14768bd46.docs.buildwithfern.com/dynamo/dev

[dagil-nvidia]

/ok to test 54e81f2

[harryskim]

Verified the substantive claims against main — this is a real correction and the old text was actively misleading.

Checks that passed:

• Axes match the code. backend_args.py:234-239 help says "Sweeps iteration-total prefill tokens/KV reads/batch size and/or decode total-KV/batch-size points", and the flags back it: prefill via --prefill-max-new-token-samples, --prefill-max-kv-read-token-samples, --prefix-max-batch-size-samples; decode via --decode-max-kv-read-token-samples, --decode-max-batch-size-samples. No ISL or (context_length × batch_size) axis exists anywhere in the sweep.
• ForwardPassMetrics is still current — 10 references in instrumented_scheduler.py.
• Net diff is 1 file / 1 line vs origin/main; no residue from the abandoned release/1.4.0 splice.
• The CodeRabbit refutation holds. --benchmark-points-file's own help text (backend_args.py:249-256) says the generated-grid sampling options "are ignored" when it is set. The existing docs wording is accurate.

Two nits — both non-blocking, but good to fix if you're touching this again:

1. as described below points the wrong way. The added trailing sentence says the axes are derived from the engine's limits "as described below", but that derivation — the {capture size, capture size + 1} boundaries and power-of-two block ladders — is in the section intro paragraph immediately above the ParamField. What's below are the per-axis sample-limit flags. The sentence also restates the opening clause of that paragraph three lines up, so dropping it entirely reads cleaner than changing "below" to "above".

2. The sentence is a mouthful. "Sweeps iteration-total prefill new-token, KV-read-token, and batch-size operating points and/or decode KV-read-token and batch-size operating points" — two comma-lists joined by "and/or" with "operating points" repeated. Faithful to the help text, which is defensible for a reference page, but something like "Sweeps prefill operating points (iteration-total new tokens, KV-read tokens, batch size) and/or decode operating points (KV-read tokens, batch size)" carries the same content without the backtrack.

Neither affects correctness or would mislead anyone about how the flag behaves, so please don't hold the merge on them.

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Out of scope for this PR, just flagging: the prefill batch-size flag is named --prefix-max-batch-size-samples while its own help text and the docs both call it prefill request-batch-size. Looks like a typo baked into the public flag and env var (DYN_PREFIX_MAX_BATCH_SIZE_SAMPLES) in #13036 — probably worth a separate issue rather than a rename here.