Dynamic allocation / ballooning memory?

[adamierymenko]

Another obvious idea: implement support for minimum and maximum memory and dynamic allocation / ballooning.

[LekKit]

That's a great idea to implement free page reporting, and that's part of recent versions of Virtio and VMWare balloon devices. I'll look into that (At last a good virtio device with no direct HW replacements, lol). There are also other good memory saving techniques in RVVM: KSM (Page merging, could also reclaim free pages in some cases) and transparent caches (Guest caches may be reclaimed by host).

Be aware however that explicit ballooning on host demand (Initial usecase of Virtio Balloon device) isn't that great of a concept: You force the guest to use less memory, and it most likely will start swapping / will OOM. It is much better to have large amount of virtual memory (zram/swap) on the host - from efficiency standpoint. Otherwise you'll just make pressure on the guest and make it suffer.