add CPU throttling metrics from cgroup cpu.stat

[JayiceZ]

fix VictoriaMetrics/VictoriaMetrics#10430

---

Summary by cubic

Expose CPU throttling metrics from cgroup cpu.stat for the current process. Works with cgroup v1 and v2 and only emits metrics when the cgroup CPU controller is enabled (addresses #10430).

• New Features
  • Added metrics: process_cgroup_cpu_periods_total, process_cgroup_cpu_throttled_periods_total, process_cgroup_cpu_throttled_seconds_total.
  • Auto-detects v1/v2 cpu.stat and parses nr_periods, nr_throttled, and throttled time; converts to seconds and skips metrics if the CPU controller isn’t enabled.

^{Written for commit 085d533. Summary will update on new commits.}

[cubic-dev-ai]

2 issues found across 1 file

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="process_metrics_linux.go">

<violation number="1" location="process_metrics_linux.go:474">
P2: writeProcessCpuThrottleMetrics dereferences ctms without guarding against the nil return from getCgroupCpuStats, which can panic when no cgroup CPU stats are available.</violation>

<violation number="2" location="process_metrics_linux.go:476">
P2: `process_cgroup_cpu_throttled_seconds_total` reports non-second units (micro/milliseconds). Convert throttled_time to seconds (or store microseconds consistently and divide by 1e6 when writing) to avoid unit mismatch.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[codecov]

Codecov Report

❌ Patch coverage is 71.26437% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.00%. Comparing base (e60b57c) to head (84e7c97).

Files with missing lines	Patch %	Lines
process_metrics_linux.go	71.26%	18 Missing and 7 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #112      +/-   ##
==========================================
- Coverage   87.96%   87.00%   -0.96%     
==========================================
  Files          12       12              
  Lines        1437     1524      +87     
==========================================
+ Hits         1264     1326      +62     
- Misses        119      137      +18     
- Partials       54       61       +7     

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[cubic-dev-ai]

No issues found across 1 file