[pve-devel] qemu live migration: bigger downtime recently

[aderumier at odiso.com]

Hi,

I have notice recently bigger downtime on qemu live migration.
(I'm not sure if it's after qemu update or qemu-server update)

migration: type=insecure

 qemu-server                          6.3-2  
 pve-qemu-kvm                         5.1.0-7   

(I'm not sure about the machine running qemu version)



Here a sample:



2021-01-22 15:28:38 starting migration of VM 226 to node 'kvm13'
(10.3.94.70)
2021-01-22 15:28:42 starting VM 226 on remote node 'kvm13'
2021-01-22 15:28:44 start remote tunnel
2021-01-22 15:28:45 ssh tunnel ver 1
2021-01-22 15:28:45 starting online/live migration on
tcp:10.3.94.70:60000
2021-01-22 15:28:45 set migration_caps
2021-01-22 15:28:45 migration speed limit: 8589934592 B/s
2021-01-22 15:28:45 migration downtime limit: 100 ms
2021-01-22 15:28:45 migration cachesize: 268435456 B
2021-01-22 15:28:45 set migration parameters
2021-01-22 15:28:45 start migrate command to tcp:10.3.94.70:60000
2021-01-22 15:28:47 migration speed: 1024.00 MB/s - downtime 2117 ms
2021-01-22 15:28:47 migration status: completed
2021-01-22 15:28:51 migration finished successfully (duration 00:00:13)
TASK OK

That's strange because I don't see the memory transfert loop logs



Migrate back to original host is working

2021-01-22 15:29:34 starting migration of VM 226 to node 'kvm2'
(::ffff:10.3.94.50)
2021-01-22 15:29:36 starting VM 226 on remote node 'kvm2'
2021-01-22 15:29:39 start remote tunnel
2021-01-22 15:29:40 ssh tunnel ver 1
2021-01-22 15:29:40 starting online/live migration on
tcp:[::ffff:10.3.94.50]:60000
2021-01-22 15:29:40 set migration_caps
2021-01-22 15:29:40 migration speed limit: 8589934592 B/s
2021-01-22 15:29:40 migration downtime limit: 100 ms
2021-01-22 15:29:40 migration cachesize: 268435456 B
2021-01-22 15:29:40 set migration parameters
2021-01-22 15:29:40 start migrate command to
tcp:[::ffff:10.3.94.50]:60000
2021-01-22 15:29:41 migration status: active (transferred 396107554,
remaining 1732018176), total 2165383168)
2021-01-22 15:29:41 migration xbzrle cachesize: 268435456 transferred 0
pages 0 cachemiss 0 overflow 0
2021-01-22 15:29:42 migration status: active (transferred 973010921,
remaining 1089216512), total 2165383168)
2021-01-22 15:29:42 migration xbzrle cachesize: 268435456 transferred 0
pages 0 cachemiss 0 overflow 0
2021-01-22 15:29:43 migration status: active (transferred 1511925476,
remaining 483463168), total 2165383168)
2021-01-22 15:29:43 migration xbzrle cachesize: 268435456 transferred 0
pages 0 cachemiss 0 overflow 0
2021-01-22 15:29:44 migration speed: 512.00 MB/s - downtime 148 ms
2021-01-22 15:29:44 migration status: completed
2021-01-22 15:29:47 migration finished successfully (duration 00:00:13)
TASK OK


Then migrate it again like the first migration is working too


2021-01-22 15:31:07 starting migration of VM 226 to node 'kvm13'
(10.3.94.70)
2021-01-22 15:31:10 starting VM 226 on remote node 'kvm13'
2021-01-22 15:31:12 start remote tunnel
2021-01-22 15:31:13 ssh tunnel ver 1
2021-01-22 15:31:13 starting online/live migration on
tcp:10.3.94.70:60000
2021-01-22 15:31:13 set migration_caps
2021-01-22 15:31:13 migration speed limit: 8589934592 B/s
2021-01-22 15:31:13 migration downtime limit: 100 ms
2021-01-22 15:31:13 migration cachesize: 268435456 B
2021-01-22 15:31:13 set migration parameters
2021-01-22 15:31:13 start migrate command to tcp:10.3.94.70:60000
2021-01-22 15:31:14 migration status: active (transferred 1092088188,
remaining 944365568), total 2165383168)
2021-01-22 15:31:14 migration xbzrle cachesize: 268435456 transferred 0
pages 0 cachemiss 0 overflow 0
2021-01-22 15:31:15 migration speed: 1024.00 MB/s - downtime 55 ms
2021-01-22 15:31:15 migration status: completed
2021-01-22 15:31:19 migration finished successfully (duration 00:00:12)
TASK OK


Any idea ? Maybe a specific qemu version bug ?