We are running libvirt 8.0.0, and sometimes live migration could not finish (because the guest is dirtying the memory too fast). We implemented a monitor that increases max downtime when it observed that "Data Remaining" bumps up. But we found a strange sequence of events from the monitor, which leads to a paused domain on the destination hypervisor:

The monitor sees Data Remaining bumping up and increases max downtime up to 20 seconds, but weird thing is that after a period of time, it started reporting "Data Remaining" and "Data Total" is both 0, but the migration job is still unfinished:

"Migration in progress - DataTotal: 85
904728064, DataRemaining: 22201458688, TimeElapsed: 20005, MaxDowntime: 500, DirtyRate: 0"

"Migration in progress - DataTotal:
85904728064, DataRemaining: 43801825280, TimeElapsed: 10005, MaxDowntime: 500, DirtyRate: 0"

"Migration in progress - DataTotal:
 85904728064, DataRemaining: 52382912512, TimeElapsed: 10004, MaxDowntime: 500, DirtyRate: 0" (DataRemaining bumps up, we start increasing max downtime)

"Migration in progress - DataTotal:
 85904728064, DataRemaining: 4219596800, TimeElapsed: 40004, MaxDowntime: 1500, DirtyRate: 0" (Last poll where we see the job info)

After which monitor logs 

"Migration in progress - DataTotal:
 0, DataRemaining: 0, TimeElapsed: 40004, MaxDowntime: 13500, DirtyRate: 0"

The domain is always running on the source hypervisor but there is a paused domain on the destination hypervisor which is paused at start up.

Trying to understand what might have happened:
- Is this a known issue for live migrating high memory activity guests and the way we interact with libvirt?
- What is the recommended way to ensure that a started live migration always run to completion if we don't care about downtime?

Appreciate any help here

Yangchen Ye