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

aderumier at odiso.com aderumier at odiso.com
Sat Jan 23 09:38:16 CET 2021


about qemu version,  

theses vms was started around 6 november, after an update of the qemu
package the 4 november.


looking at proxmox repo, I think it should be 5.1.0-4 or -5.


pve-qemu-kvm-dbg_5.1.0-4_amd64.deb                 29-Oct-2020 17:28  
75705544
pve-qemu-kvm-dbg_5.1.0-5_amd64.deb                 04-Nov-2020 17:41  
75737556
pve-qemu-kvm-dbg_5.1.0-6_amd64.deb                 05-Nov-2020 18:08  
75693264


Could it be a known bug introduced by new backups dirty-bitmap patches,
and fixed later ?  (I see a -6 version one day later)



Le vendredi 22 janvier 2021 à 19:55 +0100, aderumier at odiso.com a
écrit :
> after some debug, it seem that it's hanging on 
> 
> $stat = mon_cmd($vmid, "query-migrate");
> 
> 
> 
> 
> result of info migrate after the end of a migration:
> 
> # info migrate
> globals:
> store-global-state: on
> only-migratable: off
> send-configuration: on
> send-section-footer: on
> decompress-error-check: on
> clear-bitmap-shift: 18
> Migration status: completed
> total time: 9671 ms
> downtime: 9595 ms
> setup: 74 ms
> transferred ram: 10445790 kbytes
> throughput: 8916.93 mbps
> remaining ram: 0 kbytes
> total ram: 12600392 kbytes
> duplicate: 544936 pages
> skipped: 0 pages
> normal: 2605162 pages
> normal bytes: 10420648 kbytes
> dirty sync count: 2
> page size: 4 kbytes
> multifd bytes: 0 kbytes
> pages-per-second: 296540
> cache size: 2147483648 bytes
> xbzrle transferred: 0 kbytes
> xbzrle pages: 0 pages
> xbzrle cache miss: 0 pages
> xbzrle cache miss rate: 0.00
> xbzrle encoding rate: 0.00
> xbzrle overflow: 0
> 
> 
> 
> 
> Le vendredi 22 janvier 2021 à 16:06 +0100, aderumier at odiso.com a
> écrit :
> > I have tried to add a log to display the current status state of
> > the
> > migration,
> > and It don't catch any "active" state, but "completed" directly.
> > 
> > Here another sample with a bigger downtime of 14s (real downtime, I
> > have checked with a ping to be sure)
> > 
> > 
> > 
> > 2021-01-22 16:02:53 starting migration of VM 391 to node 'kvm13'
> > (10.3.94.70)
> > 2021-01-22 16:02:53 starting VM 391 on remote node 'kvm13'
> > 2021-01-22 16:02:55 start remote tunnel
> > 2021-01-22 16:02:56 ssh tunnel ver 1
> > 2021-01-22 16:02:56 starting online/live migration on
> > tcp:10.3.94.70:60000
> > 2021-01-22 16:02:56 set migration_caps
> > 2021-01-22 16:02:56 migration speed limit: 8589934592 B/s
> > 2021-01-22 16:02:56 migration downtime limit: 100 ms
> > 2021-01-22 16:02:56 migration cachesize: 2147483648 B
> > 2021-01-22 16:02:56 set migration parameters
> > 2021-01-22 16:02:56 start migrate command to tcp:10.3.94.70:60000
> > 
> > 
> > 
> > 2021-01-22 16:03:11 status: completed ---> added log
> > 2021-01-22 16:03:11 migration speed: 1092.27 MB/s - downtime 14424
> > ms
> > 2021-01-22 16:03:11 migration status: completed
> > 2021-01-22 16:03:14 migration finished successfully (duration
> > 00:00:21)
> > TASK OK
> > 
> > 
> > 
> >     my $merr = $@;
> >     $self->log('info', "migrate uri => $ruri failed: $merr") if
> > $merr;
> > 
> >     my $lstat = 0;
> >     my $usleep = 1000000;
> >     my $i = 0;
> >     my $err_count = 0;
> >     my $lastrem = undef;
> >     my $downtimecounter = 0;
> >     while (1) {
> >         $i++;
> >         my $avglstat = $lstat ? $lstat / $i : 0;
> > 
> >         usleep($usleep);
> >         my $stat;
> >         eval {
> >             $stat = mon_cmd($vmid, "query-migrate");
> >         };
> >         if (my $err = $@) {
> >             $err_count++;
> >             warn "query migrate failed: $err\n";
> >             $self->log('info', "query migrate failed: $err");
> >             if ($err_count <= 5) {
> >                 usleep(1000000);
> >                 next;
> >             }
> >             die "too many query migrate failures - aborting\n";
> >         }
> > 
> >         $self->log('info', "status: $stat->{status}");   ---> added
> > log
> > 
> > 
> > Le vendredi 22 janvier 2021 à 15:34 +0100, aderumier at odiso.com a
> > écrit :
> > > 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 ?
> > > 
> > > 
> > > 
> > > 
> > 
> > 
> 
> 





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