Comparing the performance of a Samsung 990 Pro SSD bare metal to a KVM guest (running on Openshift with OSV).
System is a 4 Socket Cascade Lake system.
During the fio test, the IOThread1 on the host is constantly at 100% CPU load, hence the assumption it's CPU bound.

The virtual disks use virtio with ionative. Performance is significant low how small queue sizes (x-axis is queue sizes), see the images fio_bm_vm_read|write.png attached.

See the full comparison is here
https://docs.google.com/spreadsheets/d/1KMz27nZUdJ1s4MnCzq0qI33E3XEQDSo0zupsWQ4X2W8/edit#gid=947649392

VM dom xml is in file lu0561.xml which was automatically created by kubevirt from the given lu0561.yaml definition.