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Diffstat (limited to 'docs/devel/migration/postcopy.rst')
| -rw-r--r-- | docs/devel/migration/postcopy.rst | 36 |
1 files changed, 17 insertions, 19 deletions
diff --git a/docs/devel/migration/postcopy.rst b/docs/devel/migration/postcopy.rst index 82e7a84..e319388 100644 --- a/docs/devel/migration/postcopy.rst +++ b/docs/devel/migration/postcopy.rst @@ -33,25 +33,6 @@ 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 interruptible 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_parameter`` is ignored (to avoid delaying requested pages that - the destination is waiting for). - Postcopy internals ================== @@ -312,3 +293,20 @@ explicitly) to be sent in a separate preempt channel, rather than queued in the background migration channel. Anyone who cares about latencies of page faults during a postcopy migration should enable this feature. By default, it's not enabled. + +Postcopy blocktime statistics +----------------------------- + +Blocktime is a postcopy live migration metric, intended to show how +long the vCPU was in state of interruptible 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. |