docs/devel/migration.rst

557 This is primarily used by postcopy, but is also used to return a success
571      Return path  - opened by main thread, written by main thread AND postcopy
580 the postcopy phase, a failure of *either* side or the network connection causes
583 In postcopy the destination CPUs are started before all the memory has been
588 doesn't finish in a given time the switch is made to postcopy.
590 Enabling postcopy
593 To enable postcopy, issue this command on the monitor (both source and
596 ``migrate_set_capability postcopy-ram on``
603 will now cause the transition from precopy to postcopy.
607 Blocktime is a postcopy live migration metric, intended to show how
611 side.  To enable postcopy blocktime calculation, enter following
614 ``migrate_set_capability postcopy-blocktime on``
617 postcopy-blocktime value of qmp command will show overlapped blocking
618 time for all vCPU, postcopy-vcpu-blocktime will show list of blocking
622   During the postcopy phase, the bandwidth limits set using
639 Until postcopy is entered the migration stream is identical to normal
640 precopy, except for the addition of a 'postcopy advise' command at
641 the beginning, to tell the destination that postcopy might happen.
642 When postcopy starts the source sends the page discard data and then
645    - Command: 'postcopy listen'
650    - Command: 'postcopy run'
655 During postcopy the source scans the list of dirty pages and sends them
667 reading the migration stream; the 'postcopy advise' and 'discard' commands
692 - On receipt of 'postcopy listen' - 3 -(i.e. the 1st command in the package)
715     Set at the start of migration if postcopy is enabled, even
717     checks that its OS has the support needed for postcopy, and performs
718     setup to ensure the RAM mappings are suitable for later postcopy.
728     during the postcopy phase, and to cause any huge pages that
759 The source side keeps two bitmaps during postcopy; 'the migration bitmap'
763 dirties pages, however during postcopy the CPUs are stopped and nothing
766 The 'unsent map' is used for the transition to postcopy. It is a bitmap that
768 the transition to postcopy mode it is combined with the migration bitmap
776 of the discard set and thus aren't valid once in postcopy.  The dirtymap
793   d) Care should be taken with the size of hugepage used; postcopy with 2MB
811 to support postcopy.
817 RAMBlock/offsets.  The client's userfaultfd is added to the postcopy
829 Retro-fitting postcopy to existing clients is possible:
832      postcopy.  In vhost-user extra messages are added to the existing