High CPU from kworker and System Interrupt Storms

📖 ~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

`kworker` threads consume high CPU, causing fan noise, lag, and power drain.

Environment & Reproduction

Common after kernel or firmware updates, especially with problematic peripherals or ACPI events.

Root Cause Analysis

Interrupt storms from faulty driver/device interactions force continuous deferred kernel work processing.

Quick Triage

Identify the hottest interrupt source before disabling random services.

Step-by-Step Diagnosis

Use `top`, `cat /proc/interrupts`, `powertop`, and `journalctl -k` to correlate spikes with devices/drivers.

Solution – Primary Fix

Update firmware and kernel, adjust problematic driver settings, and test by unplugging suspect devices or disabling features.

Solution – Alternative Approaches

Pin to stable kernel branch or apply vendor-recommended module parameters for known hardware quirks.

Verification & Acceptance Criteria

CPU usage normalizes, interrupt rate drops, and system responsiveness returns under typical workload.

Rollback Plan

Revert kernel/module parameter changes and boot previous stable kernel entry.

Prevention & Hardening

Track hardware firmware baselines and validate updates on representative hardware before rollout.

Related Errors & Cross-Refs

ACPI spam in kernel logs, thermal throttling alerts, and driver IRQ warning messages.

Related tutorial: View the step-by-step tutorial for Ubuntu 26.04 LTS.

View all Ubuntu 26.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Linux kernel interrupt diagnostics guides and Ubuntu hardware enablement notes.