IBM AIX 7.3 – Common Problem 64 – Diagnosis and Fix

📖 ~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

topas/nmon show CPU at 100% with sustained run queue on AIX 7.3 LPAR.

Environment & Reproduction

Multi-threaded workload saturates entitled capacity on shared LPAR.

Root Cause Analysis

Insufficient entitled CPU or SMT mode not optimal for workload.

Quick Triage

Run topas -P and ps -mo THREAD to identify hot processes.

Step-by-Step Diagnosis

Use curt and tprof -kse -x sleep 30 for kernel/user CPU breakdown.

Solution – Primary Fix

DLPAR add entitled capacity from HMC and tune SMT with smtctl -t 8.

Solution – Alternative Approaches

Renice low-priority work with renice or move app to dedicated LPAR.

Verification & Acceptance Criteria

topas run queue drops and entitlement consumption <80%.

Rollback Plan

Revert smtctl with smtctl -t and remove DLPAR add.

Prevention & Hardening

Right-size entitlement and monitor with nmon/PerfPMR.

Related Errors & Cross-Refs

PROC_CPU_HIGH events, slow app responsiveness.

Related tutorial: View the step-by-step tutorial for aix-7.3.

View all aix-7.3 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

AIX performance tools (topas, nmon, curt) reference.