Add Swap and Tune Performance on Your Opus Host VPS

A free VPS gives you a modest amount of RAM, and it does not take much to hit the ceiling. When memory runs out, the Linux kernel starts killing processes, usually the one you cared about most. A swap file gives the kernel breathing room by letting it move inactive memory to disk.

Swap uses disk space and is much slower than RAM. Use it as a safety net for occasional spikes, not as a substitute for enough memory. Check your resource limits before adding a large swap file.

Add a swap file

Check current swap

free -h
swapon --show

Create a 1 GB swap file

sudo fallocate -l 1G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile

Make it persistent across reboots

echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

Verify

free -h

Tune swappiness

Swappiness controls how eagerly the kernel moves memory to swap. On a server, a lower value keeps active data in RAM longer.

# Check current value (default is usually 60)
cat /proc/sys/vm/swappiness

# Set to 10 for this session
sudo sysctl vm.swappiness=10

# Make it permanent
echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf

Diagnose slow performance

Check memory and CPU

free -h        # memory usage
uptime         # load average
top            # live process view (press q to quit)
htop           # nicer top; install with: sudo apt install htop

Find the biggest memory hogs

ps aux --sort=-%mem | head -n 10

Find the biggest CPU hogs

ps aux --sort=-%cpu | head -n 10

Check disk usage

df -h          # disk space by mount
du -sh /*      # size of each top-level directory

Check disk I/O

sudo apt install sysstat -y
iostat -x 2 5

Remove a swap file

sudo swapoff /swapfile
sudo sed -i '/\/swapfile/d' /etc/fstab
sudo rm /swapfile

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Add Swap and Tune Performance on Your Opus Host VPS

Add a swap file

Tune swappiness

Diagnose slow performance

Check memory and CPU

Find the biggest memory hogs

Find the biggest CPU hogs

Check disk usage

Check disk I/O

Remove a swap file

​Add a swap file

​Tune swappiness

​Diagnose slow performance

​Check memory and CPU

​Find the biggest memory hogs

​Find the biggest CPU hogs

​Check disk usage

​Check disk I/O

​Remove a swap file

Add a swap file

Tune swappiness

Diagnose slow performance

Check memory and CPU

Find the biggest memory hogs

Find the biggest CPU hogs

Check disk usage

Check disk I/O

Remove a swap file