Pertemuan 13

Optimasi Sistem Linux

Tuning performa CPU, memory, disk I/O, dan network untuk optimalisasi sistem

Tujuan Pembelajaran

Setelah menyelesaikan praktikum ini, mahasiswa mampu:

  • Menganalisis bottleneck kinerja sistem Linux
  • Mengoptimasi penggunaan CPU, memory, disk I/O, dan network
  • Mengkonfigurasi kernel parameters untuk performa optimal
  • Mengimplementasikan filesystem dan storage optimization
  • Melakukan tuning pada layanan sistem untuk performa maksimal

Teori Pendukung

Area Optimasi Sistem
CPU Optimization

Process scheduling, CPU frequency scaling, affinity settings

Memory Optimization

Swappiness, cache management, hugepages, transparent hugepages

Disk I/O Optimization

Filesystem tuning, I/O schedulers, RAID optimization

Network Optimization

TCP/IP stack tuning, buffer sizes, interface settings

Performance Analysis Framework
1. Identify Bottleneck

Monitoring melalui tools dan identifikasi sumber masalah

2. Analyze Root Cause

Analisis mendalam penyebab bottleneck

3. Implement Optimization

Penerapan teknik optimasi yang tepat

4. Validate Improvement

Benchmarking dan verifikasi peningkatan performa

5. Monitor Changes

Pemantauan berkelanjutan setelah optimasi

Performance Bottleneck Identification
Symptom Possible Bottleneck Diagnosis Tools
High CPU load, slow response CPU saturation, inefficient code top, perf, strace
High memory usage, swapping Memory leak, insufficient RAM free, vmstat, valgrind
Slow disk operations I/O bottleneck, disk contention iostat, iotop, fio
Network latency, packet loss Network congestion, misconfiguration ping, traceroute, netstat

Persiapan Environment dan Benchmark Baseline

1. Install Tools Optimasi dan Benchmarking
# Install tools optimasi dan benchmarking lengkap
sudo apt update && sudo apt upgrade -y
sudo apt install sysctlutils tuned hdparm iotop ionice stress-ng fio iperf3 -y

# Install kernel tools untuk CPU optimization
sudo apt install linux-tools-common linux-tools-generic cpufrequtils -y

# Buat direktori untuk praktikum optimasi
sudo mkdir -p /optimization/{benchmarks,logs,scripts}
sudo chmod 755 /optimization
2. Catat Konfigurasi Sistem Awal
# System information baseline
sudo hostnamectl > /optimization/logs/system_info.txt
sudo lscpu >> /optimization/logs/system_info.txt
sudo free -h >> /optimization/logs/system_info.txt
sudo df -h >> /optimization/logs/system_info.txt

# Kernel parameters baseline
sudo sysctl -a | grep -E "(vm|net|kernel)" > /optimization/logs/kernel_params_before.txt
3. Baseline Performance Benchmark
# CPU benchmark baseline
sysbench cpu --cpu-max-prime=20000 run > /optimization/benchmarks/cpu_before.txt

# Memory benchmark baseline
sysbench memory --memory-total-size=2G run > /optimization/benchmarks/memory_before.txt

# Disk I/O benchmark baseline
fio --name=baseline --rw=randrw --bs=4k --size=1G --numjobs=4 --runtime=60s --output=/optimization/benchmarks/disk_before.txt

CPU Performance Optimization

1. Analisis Konfigurasi CPU Saat Ini
# Informasi detail CPU
lscpu
cat /proc/cpuinfo | grep -E "processor|model name|cache|MHz"

# CPU frequency scaling info
cpupower frequency-info
cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

# Check available governors
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
2. Optimasi CPU Frequency Governor
# Set performance governor untuk maksimal performance
sudo cpupower frequency-set -g performance

# Atau conservative untuk balance performance-power
sudo cpupower frequency-set -g conservative

# Set minimum dan maximum frequency
sudo cpupower frequency-set -d 1.0GHz -u 3.0GHz

# Monitor CPU frequency real-time
watch -n 1 'cat /proc/cpuinfo | grep "MHz"'
3. Process Scheduling Optimization
# Check current I/O scheduler
cat /sys/block/sda/queue/scheduler

# Untuk desktop: set ke deadline atau cfg
echo deadline | sudo tee /sys/block/sda/queue/scheduler

# Untuk server: set ke noop atau deadline
echo noop | sudo tee /sys/block/sda/queue/scheduler

# Untuk SSD: noop recommended
echo noop | sudo tee /sys/block/nvme0n1/queue/scheduler
4. CPU Affinity untuk Critical Processes
# Set affinity process ke CPU tertentu
taskset -cp 0,1 $(pgrep nginx)

# Jalankan process dengan affinity tertentu
taskset -c 0,1 stress-ng --cpu 2 --timeout 30s

# Check current affinity
taskset -cp $(pgrep nginx)

# IRQ affinity optimization
echo 2 | sudo tee /proc/irq/24/smp_affinity
5. CPU Governor Comparison
Governor Performance Power Usage Use Case
performance Maximum High Servers, high-performance computing
ondemand Good Medium Desktop, balanced systems
conservative Medium Low Battery-powered devices
powersave Minimum Very Low Mobile devices, energy saving

Memory Optimization

1. Analisis Memory Usage Pattern
# Detailed memory info
cat /proc/meminfo
sudo slabtop -o

# Memory usage per process
ps aux --sort=-%mem | head -10

# Check memory fragmentation
cat /proc/buddyinfo
cat /proc/pagetypeinfo
2. Optimasi Swappiness
# Check current swappiness (0-100)
cat /proc/sys/vm/swappiness

# Untuk server database: set rendah (1-10)
echo 10 | sudo tee /proc/sys/vm/swappiness

# Untuk desktop: set medium (30-60)
echo 60 | sudo tee /proc/sys/vm/swappiness

# Permanent setting
echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf
3. Transparent HugePages Optimization
# Check THP status
cat /sys/kernel/mm/transparent_hugepage/enabled

# Disable untuk database workloads
echo never | sudo tee /sys/kernel/mm/transparent_hugepage/enabled

# Permanent setting via grub
sudo nano /etc/default/grub
# Tambah: transparent_hugepage=never
sudo update-grub
4. Memory Overcommit Settings
# Check overcommit ratio
cat /proc/sys/vm/overcommit_ratio
cat /proc/sys/vm/overcommit_memory

# Adjust untuk memory-intensive applications
echo 80 | sudo tee /proc/sys/vm/overcommit_ratio
echo 0 | sudo tee /proc/sys/vm/overcommit_memory

# Untuk applications yang membutuhkan large memory allocation
echo 2 | sudo tee /proc/sys/vm/overcommit_memory
5. Memory Management Parameters
Parameter Default Optimized Description
vm.swappiness 60 10 Tendency to swap (0-100)
vm.dirty_ratio 20 10 % memory for dirty pages
vm.dirty_background_ratio 10 5 % memory for background writes
vm.vfs_cache_pressure 100 50 Tendency to reclaim cache

Disk I/O Optimization

1. Filesystem Benchmarking
# Benchmark disk dengan fio - random write
fio --name=random-write --ioengine=posixaio --rw=randwrite --bs=4k --size=1g --numjobs=1 \
--iodepth=1 --runtime=60 --time_based --end_fsync=1 > /optimization/benchmarks/fio_randwrite.txt

# Benchmark sequential read
fio --name=sequential-read --ioengine=posixaio --rw=read --bs=1M --size=1g --numjobs=1 \
--iodepth=16 --runtime=60 --time_based > /optimization/benchmarks/fio_seqread.txt

# Check disk health dan performance
sudo hdparm -Tt /dev/sda
sudo smartctl -a /dev/sda
2. I/O Scheduler Tuning
# List available schedulers
cat /sys/block/sda/queue/scheduler

# Untuk SSD: set noop atau none
echo noop | sudo tee /sys/block/sda/queue/scheduler

# Untuk HDD: set deadline atau cfg
echo deadline | sudo tee /sys/block/sda/queue/scheduler

# Adjust queue depth
echo 256 | sudo tee /sys/block/sda/queue/nr_requests

# Permanent setting via udev rules
sudo nano /etc/udev/rules.d/60-ioschedulers.rules
# ACTION=="add|change", KERNEL=="sd*", ATTR{queue/scheduler}="noop"
3. Filesystem Mounting Options
# Edit fstab untuk optimal mount options
sudo nano /etc/fstab

# Untuk SSD: add noatime,nodiratime,discard
# UUID=xxx / ext4 noatime,nodiratime,discard,errors=remount-ro 0 1

# Untuk HDD: add noatime,nodiratime
# UUID=xxx / ext4 noatime,nodiratime,errors=remount-ro 0 1

# Untuk database workloads
# UUID=xxx /var/lib/mysql ext4 noatime,nodiratime,data=writeback 0 2

# Remount dengan options baru
sudo mount -o remount /
4. RAID Optimization
# Check RAID status jika ada
cat /proc/mdstat

# Optimasi read-ahead untuk RAID
echo 16384 | sudo tee /sys/block/md0/queue/read_ahead_kb

# Stripe size optimization
sudo mdadm --detail /dev/md0 | grep "Chunk Size"

# RAID controller cache settings
sudo /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp -Direct -LAll -a0
sudo /opt/MegaRAID/MegaCli/MegaCli64 -LDSetProp -Cached -LAll -a0
5. I/O Scheduler Comparison
Scheduler Best For Advantages Disadvantages
CFQ HDD, Desktop Fair queuing, good for multiple processes Higher CPU overhead
Deadline Database, Server Guaranteed latency, good for mixed workloads Complex implementation
NOOP SSD, Virtual Minimal overhead, simple FIFO No prioritization
Kyber NVMe, Fast SSD Modern, latency-based New, less tested

Network Optimization

1. TCP/IP Stack Tuning
# Current TCP settings
sysctl -a | grep tcp

# Optimasi untuk high-throughput
echo 'net.core.rmem_max = 16777216' | sudo tee -a /etc/sysctl.conf
echo 'net.core.wmem_max = 16777216' | sudo tee -a /etc/sysctl.conf
echo 'net.ipv4.tcp_rmem = 4096 87380 16777216' | sudo tee -a /etc/sysctl.conf
echo 'net.ipv4.tcp_wmem = 4096 16384 16777216' | sudo tee -a /etc/sysctl.conf

# Apply changes
sudo sysctl -p
2. Network Buffer Optimization
# Increase buffer sizes
echo 'net.core.netdev_max_backlog = 30000' | sudo tee -a /etc/sysctl.conf
echo 'net.core.somaxconn = 1024' | sudo tee -a /etc/sysctl.conf
echo 'net.ipv4.tcp_max_syn_backlog = 2048' | sudo tee -a /etc/sysctl.conf

# TCP congestion control
echo 'net.ipv4.tcp_congestion_control = cubic' | sudo tee -a /etc/sysctl.conf
# Untuk high-speed networks: BBR
echo 'net.ipv4.tcp_congestion_control = bbr' | sudo tee -a /etc/sysctl.conf
3. Network Interface Tuning
# Check interface settings
ethtool ens33

# Enable jumbo frames jika didukung
sudo ip link set ens33 mtu 9000

# Optimasi interrupt coalescing
sudo ethtool -C ens33 rx-usecs 100 tx-usecs 100

# Enable TCP segmentation offload
sudo ethtool -K ens33 tso on gso on

# RX/TX ring buffer optimization
sudo ethtool -G ens33 rx 4096 tx 4096
4. Network Stack Parameters
Parameter Default Optimized Description
net.core.rmem_max 212992 16777216 Max receive buffer size
net.core.wmem_max 212992 16777216 Max send buffer size
net.core.somaxconn 128 1024 Max pending connections
net.ipv4.tcp_fin_timeout 60 30 TCP FIN timeout
net.ipv4.tcp_tw_reuse 0 1 Reuse TIME_WAIT sockets

Kernel Parameter Tuning

1. System-wide Kernel Optimization
# Edit sysctl.conf untuk optimasi komprehensif
sudo nano /etc/sysctl.conf

# Tambahkan parameter optimasi
echo '# Performance Optimization' | sudo tee -a /etc/sysctl.conf
echo 'vm.dirty_ratio = 10' | sudo tee -a /etc/sysctl.conf
echo 'vm.dirty_background_ratio = 5' | sudo tee -a /etc/sysctl.conf
echo 'vm.vfs_cache_pressure = 50' | sudo tee -a /etc/sysctl.conf
echo 'net.ipv4.tcp_slow_start_after_idle = 0' | sudo tee -a /etc/sysctl.conf
echo 'net.ipv4.tcp_tw_reuse = 1' | sudo tee -a /etc/sysctl.conf

# Apply changes
sudo sysctl -p
2. File Descriptor Limits
# Check current limits
ulimit -n
cat /proc/sys/fs/file-max

# Increase system-wide limits
echo 'fs.file-max = 1000000' | sudo tee -a /etc/sysctl.conf

# Increase user limits
echo '* soft nofile 1000000' | sudo tee -a /etc/security/limits.conf
echo '* hard nofile 1000000' | sudo tee -a /etc/security/limits.conf

# Untuk specific service
echo 'nginx soft nofile 65536' | sudo tee -a /etc/security/limits.conf
echo 'nginx hard nofile 65536' | sudo tee -a /etc/security/limits.conf
3. Kernel Module Parameters
# Tune elevator algorithm parameters
echo 'elevator=deadline' | sudo tee -a /etc/modprobe.d/i-o.conf

# TCP module parameters
echo 'options tcp_bbr enabled=1' | sudo tee -a /etc/modprobe.d/tcp_bbr.conf

# Update initramfs
sudo update-initramfs -u

Service-specific Optimization

1. Web Server Optimization (Nginx)
# Optimasi Nginx configuration
sudo nano /etc/nginx/nginx.conf

# Worker processes = CPU cores
worker_processes auto;

# Connection optimization
events {
worker_connections 1024;
multi_accept on;
use epoll;
}

# Buffer optimization
client_body_buffer_size 10K;
client_header_buffer_size 1k;
client_max_body_size 8m;
large_client_header_buffers 2 1k;

# Gzip compression
gzip on;
gzip_types text/plain text/css application/json application/javascript;
2. Database Optimization (MySQL)
# MySQL configuration tuning
sudo nano /etc/mysql/my.cnf

# InnoDB buffer pool = 70-80% of available RAM
innodb_buffer_pool_size = 2G

# Other optimizations
innodb_log_file_size = 256M
innodb_flush_log_at_trx_commit = 2
query_cache_size = 64M
max_connections = 200

# MyISAM optimizations (jika digunakan)
key_buffer_size = 256M
myisam_sort_buffer_size = 64M
3. Application-specific Tuning
# PHP-FPM optimization
sudo nano /etc/php/7.4/fpm/pool.d/www.conf

# Process manager settings
pm = dynamic
pm.max_children = 50
pm.start_servers = 10
pm.min_spare_servers = 5
pm.max_spare_servers = 15

# Memory limits
php_admin_value[memory_limit] = 256M

Automated Tuning dengan Tuned

1. Install dan Konfigurasi Tuned
sudo apt install tuned -y
sudo systemctl enable tuned
sudo systemctl start tuned
2. Pilih Profile yang Sesuai
# List available profiles
sudo tuned-adm list

# Untuk server throughput
sudo tuned-adm profile throughput-performance

# Untuk latency-sensitive applications
sudo tuned-adm profile latency-performance

# Untuk virtual machines
sudo tuned-adm profile virtual-guest

# Untuk desktop
sudo tuned-adm profile desktop
3. Custom Tuned Profile
# Buat custom profile
sudo mkdir /etc/tuned/my-custom-profile
sudo nano /etc/tuned/my-custom-profile/tuned.conf

[main]
summary=Custom Optimized Profile

[cpu]
governor=performance
energy_perf_bias=performance

[vm]
transparent_hugepages=never
dirty_ratio=10
dirty_background_ratio=5

[disk]
elevator=deadline

# Aktifkan custom profile
sudo tuned-adm profile my-custom-profile

Performance Benchmarking dan Validation

1. Comprehensive System Benchmark
# CPU benchmark setelah optimasi
stress-ng --cpu 0 --cpu-method matrixprod --metrics-brief --timeout 30s

# Memory benchmark setelah optimasi
stress-ng --vm 1 --vm-bytes 1G --timeout 30s --metrics-brief

# Disk I/O benchmark setelah optimasi
fio --name=benchmark --rw=randrw --bs=4k --size=1G --numjobs=4 --time_based --runtime=60s

# Network benchmark setelah optimasi
iperf3 -c target_host -t 30 -P 4
2. Before/After Comparison Script
cat > /optimization/scripts/benchmark_compare.sh << 'EOF'

#!/bin/bash
echo "=== BEFORE OPTIMIZATION ===" > /optimization/benchmarks/comparison.txt
sysbench cpu run >> /optimization/benchmarks/comparison.txt
echo "" >> /optimization/benchmarks/comparison.txt

# Lakukan optimasi...

echo "=== AFTER OPTIMIZATION ===" >> /optimization/benchmarks/comparison.txt
sysbench cpu run >> /optimization/benchmarks/comparison.txt
EOF

chmod +x /optimization/scripts/benchmark_compare.sh

Monitoring Post-Optimization

1. Real-time Performance Monitoring
cat > /optimization/scripts/monitor_perf.sh << 'EOF'

#!/bin/bash
while true; do
echo "=== $(date) ==="
echo "CPU: $(top -bn1 | grep "Cpu(s)" | awk '{print $2}')%"
echo "Memory: $(free -h | grep Mem | awk '{print $3"/"$2}')"
echo "Load: $(cat /proc/loadavg | awk '{print $1,$2,$3}')"
echo "I/O: $(iostat -d 1 1 | grep sda | awk '{print $3"kB/s read",$4"kB/s write"}')"
echo "---"
sleep 5
done
EOF

chmod +x /optimization/scripts/monitor_perf.sh
2. Long-term Performance Tracking
# Setup sar untuk long-term monitoring
sudo sed -i 's/ENABLED="false"/ENABLED="true"/' /etc/default/sysstat
sudo systemctl enable sysstat
sudo systemctl start sysstat

# Generate daily performance reports
echo "0 6 * * * root /usr/bin/sar -A -o /var/log/sa/sa`date +%d`" | sudo tee -a /etc/crontab

Tugas dan Evaluasi

  1. Apa perbedaan antara CPU governor "performance" dan "powersave"? Kapan masing-masing sebaiknya digunakan?
  2. Bagaimana cara menentukan nilai optimal untuk swappiness pada server database vs web server?
  3. Apa keuntungan menggunakan I/O scheduler "noop" untuk SSD dibandingkan "cfq"?
  4. Bagaimana cara mengidentifikasi bottleneck antara CPU, memory, disk I/O, dan network?
  5. Buat skenario: Server database mengalami kinerja lambat. Tulis langkah-langkah optimasi sistematis yang akan dilakukan!

Case Study: E-commerce Server Optimization

#!/bin/bash
# E-commerce Server Optimization Script

echo "Starting e-commerce server optimization..."

# 1. CPU Optimization
cpupower frequency-set -g performance
echo "performance" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

# 2. Memory Optimization
echo 10 > /proc/sys/vm/swappiness
echo "never" > /sys/kernel/mm/transparent_hugepage/enabled

# 3. Disk I/O Optimization (SSD)
echo "noop" > /sys/block/sda/queue/scheduler
echo 256 > /sys/block/sda/queue/nr_requests

# 4. Network Optimization
echo 'net.core.somaxconn = 2048' >> /etc/sysctl.conf
echo 'net.ipv4.tcp_tw_reuse = 1' >> /etc/sysctl.conf
echo 'net.core.rmem_max = 16777216' >> /etc/sysctl.conf

# 5. Apply all changes
sysctl -p

echo "Optimization completed. Please reboot for full effect."
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