Ubuntu 18.04 LTS – swap usage stays high after memory pressure event

📖 ~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 remains sluggish because swap stays elevated long after peak usage.

Environment & Reproduction

Observed after transient memory spikes on hosts with conservative vm.swappiness defaults.

Root Cause Analysis

Kernel keeps swapped pages until memory pressure and access patterns justify reclaim.

Quick Triage

Check active memory pressure, swapin rates, and top memory consumers.

Step-by-Step Diagnosis

Analyze vmstat trends, page faults, and swappiness settings.

Solution – Primary Fix

Tune swappiness, reduce memory spikes, and restart leak-prone services if necessary.

Solution – Alternative Approaches

Increase RAM or use zswap/zram strategy for constrained environments.

Verification & Acceptance Criteria

Interactive latency normalizes and swap activity remains within baseline expectations.

Rollback Plan

Revert kernel memory tuning if workload behavior deteriorates under new settings.

Prevention & Hardening

Implement memory pressure alerting and capacity reviews for peak periods.

Related Errors & Cross-Refs

High swap usage, major page faults, and OOM near-miss incident patterns.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

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References & Further Reading

Linux memory management, swappiness tuning, and swap performance practices.