Ubuntu 20.04 LTS Excessive Swap Usage Causes Slowness

📖 ~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

Interactive and service performance degrade due to memory pressure and frequent paging.

Environment & Reproduction

Occurs on memory-constrained VMs, oversized JVM workloads, and cache-heavy services.

Root Cause Analysis

Insufficient RAM headroom and swappiness behavior push active pages to swap too aggressively.

Quick Triage

Measure memory pressure, swap in/out rates, and identify top resident memory consumers.

Step-by-Step Diagnosis

Correlate vmstat patterns with process-level memory profiles and kernel pressure indicators.

Solution – Primary Fix

Tune swappiness, optimize memory-hungry workloads, and increase RAM or right-size service allocations.

Solution – Alternative Approaches

Use zswap or zram, reduce background services, or enforce workload memory limits.

Verification & Acceptance Criteria

Swap churn drops significantly and latency-sensitive services meet baseline response objectives.

Rollback Plan

Revert kernel memory tunables and application limits if new settings cause instability.

Prevention & Hardening

Establish memory capacity planning and continuous pressure monitoring in production environments.

Related Errors & Cross-Refs

Frequently linked to OOM killer events and database latency spikes.

Related tutorial: View the step-by-step tutorial for Ubuntu 20.04 LTS.

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Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Review Ubuntu kernel memory management and performance tuning resources.