VM file cache swapped on the host?

[Christopher Pereira]

1) Can someone please confirm this response from ChatGPT?

# Me:
is the ram used by a qemu-kvm VM as file cache swapped on the host when 
the host is low on ram?

# ChatGPT:
No, the RAM used by a QEMU-KVM (Kernel-based Virtual Machine) VM as file 
cache is not directly swapped on the host when the host is low on RAM. 
In a virtualized environment, the host manages the physical memory, and 
each VM operates within its allocated virtual memory space.

When the host is low on RAM, it may resort to swapping out its own 
processes or data to disk to free up memory. However, the content of the 
VM's RAM, including file cache, is typically managed separately. The 
host's memory management doesn't directly affect the VM's memory content.

It's worth noting that the VM's memory may be swapped within the VM 
itself if it's configured to use swap space. This is independent of what 
is happening on the host. If the VM's own memory management decides to 
swap some of its content to disk, it will do so within the virtualized 
environment.

2) If ChatGPT is right, I wonder how the host can know which RAM is used 
as file cache by the VM in order to treat it separately.

3) Related. Can you also please confirm my comments posted here some 
years ago:
https://unix.stackexchange.com/a/702729/526077
https://forum.proxmox.com/threads/vm-swap-best-practice.126514/