@@ -402,6 +402,19 @@ 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
the destination is waiting for).