Severe swap thrashing and poor performance

📖 ~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 latency spikes and throughput drops as system spends time paging memory.

Environment & Reproduction

RHEL 7 virtual host with constrained RAM and memory-intensive workload peaks.

Root Cause Analysis

Oversubscribed memory, high swappiness defaults for workload, or memory leak in process.

Quick Triage

Use vmstat 1, free -m, and top to detect sustained swap-in/swap-out activity.

Step-by-Step Diagnosis

Profile memory consumers with smem/ps, inspect OOM events in journalctl -k, and check cgroup limits.

Solution – Primary Fix

Lower vm.swappiness appropriately, stop leak process, and add RAM or tune app memory footprint.

Solution – Alternative Approaches

Create dedicated swap LV for burst tolerance while long-term capacity remediation is planned.

Verification & Acceptance Criteria

Swap activity normalizes and application latency returns to service-level targets.

Rollback Plan

Revert sysctl swappiness setting and restart affected application if behavior worsens.

Prevention & Hardening

Baseline memory telemetry and set proactive alerts for sustained swap and page fault spikes.

Related Errors & Cross-Refs

kswapd high CPU, OOM killer messages, application timeout under load.

Related tutorial: View the step-by-step tutorial for rhel-7.

View all rhel-7 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

RHEL performance tuning guide, sysctl vm settings, Linux memory management references.