I think we're losing the topic here. The way that qemu allocates memory is that generally it allocates 100% of the memory you've given to the VM (sans virtio b

I think we're losing the topic here. The way that qemu allocates memory is that generally it allocates 100% of the memory you've given to the VM (sans virtio balloon, which the VM doesn't really know about and will accidentally use for filesystem caches). This makes qemu-kvm look like a program that uses a lot of memory, and linux (as a host) doesn't know what's happening inside and is not doing anything smart with free memory inside a VM. This is true with many caveats, such as KSM (kernel-shared-memory), and the nature of virtio ballooning. This is the foundation of how it's working, which is what my parent comment was asking.