Now that Ubuntu (since 17.04) uses a swap file instead of a swap partition, can the swap settings be adjusted with the same methods used for swap partitions?
For example, to set your swap to 40, will
sudo sysctl vm.swappiness=40
still work?
And will adding vm.swappiness = 40 to /etc/sysctl.conf retain the new settings after restart?
Yes to both. Swappiness will be set the same way for swap files and swap partitions. I would recommend using a separate configuration file in /etc/sysctl.d/ though.
To check whether the swappiness has been set after reboot, use the following command:
$ cat /proc/sys/vm/swappiness
40
If you want to test that the swappiness does actually change, you can do a simple test as described in this article: https://rudd-o.com/linux-and-free-software/tales-from-responsivenessland-why-linux-feels-slow-and-how-to-fix-that.
Take also note of this question discussing the pros and cons of reducing swappiness: Why most people recommend to reduce swappiness to 10-20?
