Observable memory usage in kvm/qemu to predict OOM

[eriknordmark]

The memory usage of kvm/qemu is not always predictable. Various adjustments have been made to take into account the various memory allocations done in qemu.
But it would be good to find a way to be able to more easily observe where and what memory it allocates so that we can improve these estimates.

[OhmSpectator]

In the scope of this task, I'm going to integrate a Memory Monitor into the EVE rootfs. Also we had some work done with the QEMU observations. So, before starting on the task, please contact me or @rouming.