I read it, and it appears that the reference is talking primarily about what the kernel does. I kept searching and couldn’t find any definitive statement that a PROGRAM could request this, however apparently some JVM somewhere can do something with memory that almost requires there be swap to keep the JVM from getting killed by the OOM monster… er, killer… er, task.. er, whatever.
From: PLUG-discuss [mailto:email@example.com] On Behalf Of Stephen Partington
Sent: Sunday, September 23, 2018 12:18 AM
To: Main PLUG discussion list
Subject: Re: To swap or not to swap ;-) (was RE: To lvm or not to lvm)
I have found some applications use swap with direct calls.
"A significant number of the pages referenced by a process early in its life may only be used for initialisation and then never used again. It is better to swap out those pages and create more disk buffers than leave them resident and unused."