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[v11,4/6] migration: postcopy_blocktime documentation

Message ID 1507202170-22619-5-git-send-email-a.perevalov@samsung.com
State New
Headers show
Series calculate blocktime for postcopy live migration | expand

Commit Message

Alexey Perevalov Oct. 5, 2017, 11:16 a.m. UTC 
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
---
 docs/devel/migration.txt | 13 +++++++++++++
 1 file changed, 13 insertions(+)
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Patch

diff --git a/docs/devel/migration.txt b/docs/devel/migration.txt
index 4030703..cebfe7a 100644
--- a/docs/devel/migration.txt
+++ b/docs/devel/migration.txt
@@ -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).