Ubuntu 18.04 LTS swap thrashing causes severe slowdown

📖 ~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 sessions freeze and application latency spikes unexpectedly.

Environment & Reproduction

Memory-constrained instance running bursty JVM and database tasks.

Root Cause Analysis

Working set exceeds RAM and kernel aggressively pages active memory.

Quick Triage

Capture free, vmstat, and top snapshots under peak load.

Step-by-Step Diagnosis

Measure page fault rates and identify top memory consumers.

Solution – Primary Fix

Tune swappiness, right-size memory, and constrain heavy processes.

Solution – Alternative Approaches

Adopt zram or workload scheduling to reduce peak contention.

Verification & Acceptance Criteria

Swap activity drops and response times stabilize within SLOs.

Rollback Plan

Restore previous sysctl values and service resource definitions.

Prevention & Hardening

Use memory alerts and capacity planning based on growth trends.

Related Errors & Cross-Refs

Distinguish OOM killer events from sustained swap pressure.

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

View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Linux VM tuning references and Ubuntu performance documentation.