[ovirt-users] Actual downtime during migration?

Hello, I was testing put host into maintenance on 4.0.6, with 1 VM running. It correctly completes the live migration of the VM and I see this event in pane: Migration completed (VM: ol65, Source: ovmsrv06, Destination: ovmsrv05, Duration: 39 seconds, Total: 39 seconds, Actual downtime: 133ms) What is considered as "Actual downtime"? Thanks, Gianluca