High CPU Usage From Kworker Or System Daemons

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

CPU remains saturated even at low application load, affecting latency and throughput.

Environment & Reproduction

Use `top`, `pidstat`, and `ps -eo pid,comm,%cpu –sort=-%cpu | head` to identify offenders.

Root Cause Analysis

Ensure firmware, kernel, and monitoring tool packages are up to date via dnf.

Quick Triage

Inspect busy units with `systemctl status` and check restart loops or crash-recovery patterns.

Step-by-Step Diagnosis

Correlate spikes with `journalctl –since -1h` and kernel events from `dmesg`.

Solution – Primary Fix

Capture tuned profile, power settings, and CPU governor state before tuning changes.

Solution – Alternative Approaches

Check for packet storms or scan traffic; review `firewalld` counters for unexpected inbound patterns.

Verification & Acceptance Criteria

Review AVC denials that may trigger repeated retries in constrained services.

Rollback Plan

Patch known bugs, tune offending service limits, and apply workload-specific kernel parameters.

Prevention & Hardening

Measure sustained CPU after fix and confirm no recurring spikes in monitoring dashboards.

Related Errors & Cross-Refs

Set CPU anomaly alerts and baseline expected worker thread behavior per host role.

Related tutorial: View the step-by-step tutorial for rhel-9.

View all rhel-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Attach perf samples, service logs, and exact kernel build information.