libvirt users - Sep 2020 - Question about reduced memory by balloon driver (QEMU specific?)

Hi guys,

When a guest's memory is dynamically reduced with setMemory API (and
"balloon" QMP API), I'm wondering whether the virtio-balloon
driver in the
guest is consuming such reduced memory.

If so, how can I see that the memory virtio-balloon is consuming?
and is it possible the virtio-balloon has such a huge memory even though
it's a kernel module??

Thanks,