TOOL » LINUX

Swap

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Reference:wiki.archlinux.org

Checking swap status ​

shell
swapon --show
free -h

Swap file ​

The following commands creates and activates a swap file of 8000 MiB.

shell
dd if=/dev/zero of=/swapfile bs=1M count=8000 status=progress
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile

Also add an entry to the swap file on /etc/fstab:

txt
/swapfile none swap defaults 0 0

Swappiness ​

Read more here.

swap_tendency behaves diferently when bellow or above 100.

c
swap_tendency = mapped_ratio/2 + distress + vm_swappiness;
  • Lower than 50: Memory is already full and having distress (trouble to free memory).
  • 50 means: Wait until we run out of memory until swapping.
  • 55 means: When memory usage is 90%, start using swap.
  • 60 means: When memory usage is 80%, start using swap.

Check the current swappiness with:

shell
sysctl vm.swappiness

Temporarily set the swappiness:

shell
sysctl -w vm.swappiness=55

To set it permanently, add to /etc/sysctl.d/99-swappiness.conf:

txt
vm.swappiness=55