Rewrite README.md with comprehensive documentation

[sayalibhavsar]

Description

Replace the minimal 70-line README with a production-quality document modeled after the autohpl-wrapper README for consistency across the Red Hat Performance wrapper family.

Before/After Comparison

Aspect	Before	After
Length	~70 lines	~520 lines
CLI options	13 options listed in a plain code block, some with incorrect defaults	All 17 options (including --etcd_opts, --file_count, --file_size, --fs_type, --lvm) documented with verified defaults
--runtime default	Usage text said "60 seconds"	Corrected to 120 seconds (matches code)
Disk sweep logic	Not documented	Full explanation with progression (1, 2, 4, 8, ... max)
Job calculation	Not documented	Documented doubling from jobs_min to jobs_max with NUMA awareness
etcd simulation	Not documented	Dedicated section with parameter table
Regression mode	One sentence	Dedicated section explaining reduced iodepth list and disk sweep
Output directory	Not documented	Full tree layout with file descriptions
CSV schema	Not documented	Column-by-column table matching header_txt in code
Result validation	Not documented	Pydantic schema fields and constraints
PCP integration	Not documented	Dedicated section covering logging, knobs, and metrics
LVM / filesystem mode	Not documented	Documented with examples
Dependencies	Single line listing wrong packages (included numactl, missing per-OS lists)	Per-OS package lists matching fio-wrapper.json
Examples	2 lines	13 example invocations covering common use cases
Troubleshooting	None	8 error messages with causes and fixes
Known limitations	None	6 items including code bugs (#65, #66)
FIO job file config	Not documented	Table of all global settings
Return codes	Not documented	Table with exit codes
Test matrix sizing	Not documented	Formula with example calculation

Clerical Stuff

This closes #67

Relates to JIRA: RPOPC-1342

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Enterprise

Run ID: be0870ba-3012-41a3-b465-607a9289be65

📥 Commits

Reviewing files that changed from the base of the PR and between 276816b and f35c61e.

📒 Files selected for processing (1)

• README.md

📝 Walkthrough

Walkthrough

README.md is fully replaced with a structured, production-quality document covering CLI options, execution workflow, FIO parameters and defaults, disk/job/engine selection, regression and etcd simulation modes, output layout, CSV schema, Pydantic result validation, PCP integration, worked examples, return codes, troubleshooting, known limitations, repository layout, and references.

Changes

README Comprehensive Rewrite

Layer / File(s)	Summary
Overview, CLI options, and workflow README.md	New title, capability bullet list, full fio_run command-line options reference with defaults, and a numbered end-to-end execution workflow covering dependency install through cleanup. Dependencies section and quick-start run instructions are also rewritten.
Benchmark parameters, output files, and validation README.md	Structured sections added for FIO parameters and defaults tables, disk selection modes (raw/file/LVM), disk sweep, job and I/O engine selection (with --etcd_opts bug note), runtime/logging, regression/etcd modes, job file config, test matrix size math, output directory layout, CSV columns/sorting, Pydantic result validation rules, and PCP integration behavior.
Examples, return codes, notes, and references README.md	Full examples section with ~15 use-case commands, explicit return codes table, notes on OS/architecture support, direct I/O, performance tips, troubleshooting strings, expanded known limitations, repository layout tree, and reference links.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly states the README rewrite and matches the main documentation update.
Description check	✅ Passed	The description includes a summary, before/after comparison, and closes the issue with JIRA context.
Linked Issues check	✅ Passed	The README rewrite covers the documented options, workflows, modes, integrations, and dependency lists from #67.
Out of Scope Changes check	✅ Passed	The changes stay within README.md documentation and do not introduce unrelated code modifications.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@README.md`:
- Line 518: Fix the typo in the LVM mode description by replacing “numb_disks”
with the correct identifier or plain English “number of disks.” Update the
README sentence under the LVM mode note so it matches the actual symbol if one
exists, likely “num_disks,” and keep the wording consistent with the rest of the
documentation.
- Line 237: The README note for the `--etcd_opts` FIO engine behavior is
incorrect: it currently says the generated config falls back to `libaio`, but
the actual behavior in the `--etcd_opts` path is that `ioe=sync` is written as
`ioengine=sync`. Update the wording in the documentation section that describes
`--etcd_opts` so it matches the implementation and references the
`ioengine`/`ioe` behavior accurately.

🪄 Autofix (Beta)

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

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Enterprise

Run ID: e0d1b98a-41b1-4ca6-b0db-99f80f96ebdd

📥 Commits

Reviewing files that changed from the base of the PR and between 494e8a3 and 276816b.

📒 Files selected for processing (1)

• README.md