Memory

Swap File

• Review: sudo swapon --show
• Resize:
  1. disable: sudo swapoff /swap.img
  2. resize: sudo fallocate -l 32G /swap.img
  3. mark the file as swap: sudo mkswap /swap.img
  4. enable swap file: sudo swapon /swap.img
• Disable:
  1. Identify the swap file sudo swapon --show.
  2. Disable swapping until the next reboot: sudo swapoff <SWAP_FILE>.
  3. Comment out the swap configuration line in /etc/fstab to permanently disable swapping.

Memory mapped files limit

• Check the current limit: sysctl vm.max_map_count
• Increase:

1. Search for the vm.max_map_count parameter the sysctl configuration files:
   • sudo grep max_map_count /etc/sysctl.conf
   • sudo grep max_map_count /etc/sysctl.d/*
2. Update the existing or insert the new map count parameter to /etc/sysctl.conf: vm.max_map_count = 1000000
3. Reload the sysctl service: sudo sysctl -p
4. Confirm that the files limit was updated: sysctl vm.max_map_count

Stress Testing

• Use stress-ng

CLI

• Free memory: free -th or cat /proc/meminfo | grep MemFree
  • refresh every second: free -th -s 1
• Top 10 processes that use most memory: ps aux --sort=-%mem | head -10