Linux: how to explicitly unswap everything possible?

Solution 1:

I'd recommend allowing the normal Linux memory control swap in the things that are actually used, as they are used.

The only thing I can think off is to turn swap off, then on again

sudo swapoff -a
sudo swapon -a

That assumes you have enough spare physical memory to contain everything in swap...

Solution 2:

You can tune it echoing some number between 0 to 100 into /proc/sys/vm/swappiness.

This control is used to define how aggressive the kernel will swap memory pages. Higher values will increase agressiveness, lower values decrease the amount of swap. A value of 0 instructs the kernel not to initiate swap until the amount of free and file-backed pages is less than the high water mark in a zone.

The default value is 60.