What I usually do is create a custom rule in
/etc/sysctl.d/ instead of editing the main
sysctl file. Change directory to
sysctl.d and create your file:
sudo touch 60-my-swappiness.conf
Then run your favourite text editor:
sudo nano 60-my-swappiness.conf
Enter your value at the top of the file, for example,
vm.swappiness = 10 (there must be spaces between swappiness and the value as shown).
As it recommends in the readme in
sudo service procps start
for the system to read the new values and then reboot.
The reason why we use
60 at the start of the
my-swappiness.conf is so that your custom rule overrides any other rules in the directory.
Check that you have the correct swappiness with
This works for me, but there is more guidance on swap and swappiness in the Ubuntu guide if you need any more detailed information.