Commit 2f7dae9d authored by Alexey Perevalov's avatar Alexey Perevalov Committed by Juan Quintela
Browse files

migration: postcopy_blocktime documentation 



Reviewed-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: default avatarAlexey Perevalov <a.perevalov@samsung.com>
Reviewed-by: default avatarJuan Quintela <quintela@redhat.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent 3be98be4

docs/devel/migration.rst

+14 −0
Original line number Diff line number Diff line
@@ -401,6 +401,20 @@ will now cause the transition from precopy to postcopy. 
It can be issued immediately after migration is started or any

time later on.  Issuing it after the end of a migration is harmless.



Blocktime is a postcopy live migration metric, intended to show how

long the vCPU was in state of interruptable sleep due to pagefault.

That metric is calculated both for all vCPUs as overlapped value, and

separately for each vCPU. These values are calculated on destination

side.  To enable postcopy blocktime calculation, enter following

command on destination monitor:



``migrate_set_capability postcopy-blocktime on``



Postcopy blocktime can be retrieved by query-migrate qmp command.

postcopy-blocktime value of qmp command will show overlapped blocking

time for all vCPU, postcopy-vcpu-blocktime will show list of blocking

time per vCPU.



.. note::

  During the postcopy phase, the bandwidth limits set using

  ``migrate_set_speed`` is ignored (to avoid delaying requested pages that