hermeticormus System performance analysis
Analyze and optimize performance on a Debian/Ubuntu Linux machine. Measure before forming an opinion; tune the bottleneck, not a guess. Confirm before any change that alters kernel parameters, kills processes, or disables services.
Performance analysis steps
1. Current-state assessment
CPU:
top -bn1 | head -20
mpstat 1 5
Look at usage patterns, per-process CPU, and load average.
Memory:
free -h
vmstat 1 5
Look at RAM usage, swap usage, and memory pressure.
Disk:
df -h
iostat -x 1 5
Look at free space, I/O performance, and per-disk utilization.
Network:
ifstat 1 5
netstat -s
Look at throughput, packet statistics, and errors or drops.
Processes:
ps aux --sort=-%mem | head -10
ps aux --sort=-%cpu | head -10
Look for resource hogs, zombie processes, and process states.
2. Identify the bottleneck
Common bottlenecks: CPU saturation, memory exhaustion, disk I/O wait, network congestion, process limits. Name which one the measurements point to before tuning.
3. Optimization strategies
For CPU: identify CPU-intensive processes, check for runaway processes, consider nice/renice, review cron jobs, optimize application code.
For memory: check for leaks, review swap usage, adjust swappiness, kill memory hogs, add RAM if genuinely needed.
For disk: check usage, clean up old files, tune the I/O scheduler, consider an SSD, check for a failing disk with smartctl.
For network: check bandwidth, review firewall rules, tune network settings, check for attacks.
4. System tuning
Kernel parameters in /etc/sysctl.conf: vm.swappiness, fs.file-max, net.core parameters.
Service optimization: disable unused services, tune service configs, review startup items.
Resource limits in /etc/security/limits.conf: open-file limits, process limits, memory limits.
5. Monitoring setup
Set up ongoing monitoring: htop for a real-time view, logging for historical data, alerts for issues, and recorded performance baselines.
6. Before-and-after comparison
Benchmark before changes, apply optimizations, benchmark after, and document the result.
Guide me through systematic performance analysis and give specific recommendations for this system.
See full content at https://github.com/HermeticOrmus/linux-sysadmin-skills.