On Fri, Jan 07, 2022 at 12:00:13AM +0000, Tian, Kevin wrote: > > Devices that are poorly designed here will have very long migration > > downtime latencies and people simply won't want to use them. > > Different usages have different latency requirement. Do we just want > people to decide whether to manage state for a device by > measurement? It doesn't seem unreasonable to allow userspace to set max timer for NDMA for SLA purposes on devices that have unbounded NDMA times. It would probably be some new optional ioctl for devices that can implement it. However, this basically gives up on the idea that a VM can be migrated as any migration can timeout and fail under this philosophy. I think that is still very poor. Optional migration really can't be sane path forward. Jason
