docs: administration: troubleshooting: document engine channel capacity warning

[eschabell]

• Document the flush requests in flight limit and its defaults
• Document the low engine channel capacity warning on Linux
• Note the fs.pipe-user-pages-soft kernel setting and that the limit isn't configurable

Signed-off-by: Eric D. Schabell eric@schabell.org

Summary by CodeRabbit

• Documentation
  • Added troubleshooting guidance for low engine channel capacity, including flush-request limits, when queued tasks are processed, and the effect of Linux pipe capacity.
  • Clarified that the reported limit can vary with system pipe capacity and that Fluent Bit has no setting to configure it.

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• administration/troubleshooting.md

📝 Walkthrough

Walkthrough

The troubleshooting guide now documents platform-specific flush-request limits, how excess tasks are handled, and how Linux pipe capacity can reduce the limit.

Changes

Engine channel capacity troubleshooting

Layer / File(s)	Summary
Document flush-request limits and capacity behavior administration/troubleshooting.md	The guide describes the flush-request limits for Linux and other platforms, explains that excess tasks start in the next flush cycle, and documents how Linux pipe capacity can lower the limit and produce a warning.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Other

Suggested reviewers: lecaros

Merge Risk: 🔵 Low · up to b28ca

Linux 5.14+ operators receive inaccurate pipe-capacity guidance; qualify the statement so the troubleshooting instructions are correct before merging.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the documentation change for the engine channel capacity warning, which is the main change in the pull request.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
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.

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[eschabell]

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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minimal, and validate.

Inline comments:
Review comments at @administration/troubleshooting.md:
- Line 67: Update the Linux pipe-capacity statement in the Fluent Bit startup
description to qualify the behavior by kernel version: pipes are limited to one
page before Linux 5.14 and two pages on Linux 5.14 and later after the soft
limit is exceeded.

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• administration/troubleshooting.md

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[eschabell]

@patrick-stephens ready for review!