If you execute the
free -m command you may notice that the operating system can use some swap even if there is still RAM free.
This behaviour is controlled by the Linux kernel parameter
vm.swappiness and can be changed by setting its value from 0 to 100.
The swappiness in Linux is a rate in which the operating system tends to write data out of the RAM onto the disk drive (HDD or SSD).
In this note i’ll show how to check and how to change the swappiness in Linux.
Cool Tip: How to disable swap in Linux! Read more →
Swappiness in Linux
||Swap usage will be avoided unless it is absolutely necessary (out of memory).|
||The default value of
||Aggressive swapping. Programs will be swapped to disk almost instantly.|
Check the current swappiness value, by typing:
$ cat /proc/sys/vm/swappiness
To change the current swappiness value, execute:
$ sudo sysctl vm.swappiness=<VALUE> - example - $ sudo sysctl vm.swappiness=60
To set the swappiness value persistently, so it stays after reboot, create the
/etc/sysctl.d/99-swappiness.conf file and define there the
vm.swappiness=<VALUE>, for example:
$ sudo echo "vm.swappiness=60" | sudo tee -a /etc/sysctl.d/99-swappiness.conf
To turn off swap (move swap contents back to the RAM) and then re-enabled it, run:
$ sudo swapoff -a $ sudo swapon -a