Debian 10 – sustained high CPU from kswapd under memory pressure – Fix & Prevention

📖 ~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

System CPU is consumed by memory reclaim threads, slowing application response.

Environment & Reproduction

Occurs during memory overcommit, large caches, or insufficient swap tuning.

Root Cause Analysis

Kernel repeatedly scans pages due to persistent reclaim pressure and imbalance.

Quick Triage

Measure memory utilization, swap activity, and top consumers by process.

Step-by-Step Diagnosis

Correlate vmstat, slab usage, and workload behavior over peak windows.

Solution – Primary Fix

Reduce memory pressure, adjust VM knobs, and right-size workload limits.

Solution – Alternative Approaches

Scale vertically or split heavy services across additional hosts.

Verification & Acceptance Criteria

kswapd CPU usage drops and latency metrics return to baseline.

Rollback Plan

Restore prior VM tunables and service allocation settings if regressions appear.

Prevention & Hardening

Set memory SLO alarms and capacity thresholds before saturation.

Related Errors & Cross-Refs

Often coupled with swap thrashing, OOM kills, and high I/O wait.

Related tutorial: View the step-by-step tutorial for Debian 10.

View all Debian 10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Linux memory reclaim and vm tuning guidance.