[Xen-users] UNDERSTANDING XEN LOG OUTPUT

["Phillip Nkubito" <phil@xxxxxxxxxxxxxxxx>]

Hi,

I am looking at the output of my xen logs (using xm log), particularly the
outputs pertaining to the migration of VMS.

Here is an excerpt from the source host's logs(dom0); I am showing the
first 3 iterations of the VM live migration.

===========================================================
1:  [2012-03-09 13:37:12 xend 3113] INFO (XendCheckpoint:498) Saving
memory pages: iter 1
2:   1: sent 28847, skipped 3921, delta 1702ms, dom0 62%, target 32%, sent
555Mb/s, dirtied 116Mb/s 6036 pages

3:  [2012-03-09 13:37:13 xend 3113] INFO (XendCheckpoint:498) Saving
memory pages: iter 2
4:   2: sent 3462, skipped 2574, delta 201ms, dom0 60%, target 44%, sent
564Mb/s, dirtied 613Mb/s 3766 pages

5:   [2012-03-09 13:37:13 xend 3113] INFO (XendCheckpoint:498) Saving
memory pages: iter 3
6:    3: sent 2701, skipped 1065, delta 178ms, dom0 48%, target 46%, sent
497Mb/s, dirtied 634Mb/s 3447 pages
===========================================================

It continues iterating as expected from the pre-copy algorithm until
eventually the VM is migrated to the destination host.

My question is what is "delta" as it appears in "line 2,4 and 6" above
supposed to be in terms of the migration time?


For my next question I am showing the last iterations and some logs xen
spews out:
===========================================================
1:  [2012-03-09 13:37:14 xend 3113] INFO (XendCheckpoint:498) Saving
memory pages: iter 12
2:   12: sent 341, skipped 0, delta 12ms, dom0 100%, target 0%, sent
931Mb/s, dirtied 114Mb/s 42 pages
3:  [2012-03-09 13:37:14 xend 3113] INFO (XendCheckpoint:498) Saving
memory pages: iter 13
4:   13: sent 42, skipped 0, Start last iteration
5:  [2012-03-09 13:37:14 xend 3113] DEBUG (XendCheckpoint:449) suspend
6:  [2012-03-09 13:37:14 xend 3113] DEBUG (XendCheckpoint:178) In
saveInputHandler suspend
7:  [2012-03-09 13:37:14 xend 3113] DEBUG (XendCheckpoint:180) Suspending
4 ...
8:  [2012-03-09 13:37:14 xend.XendDomainInfo 3113] DEBUG
(XendDomainInfo:1335) XendDomainInfo.handleShutdownWatch
9:  [2012-03-09 13:37:14 xend.XendDomainInfo 3113] DEBUG
(XendDomainInfo:1335) XendDomainInfo.handleShutdownWatch
10: [2012-03-09 13:37:14 xend.XendDomainInfo 3113] INFO
(XendDomainInfo:1292) Domain has shutdown: name=migrating-vm2 id=4
reason=suspend.
11: [2012-03-09 13:37:14 xend 3113] INFO (XendCheckpoint:185) Domain 4
suspended.
12: [2012-03-09 13:37:14 xend 3113] INFO (XendCheckpoint:498) SUSPEND
shinfo 00000bdc
13: [2012-03-09 13:37:14 xend 3113] INFO (XendCheckpoint:498) delta 11ms,
dom0 81%, target 0%, sent 125Mb/s, dirtied 199Mb/s 67 pages
14: [2012-03-09 13:37:14 xend 3113] INFO (XendCheckpoint:498) Saving
memory pages: iter 14
15:  14: sent 67, skipped 0, delta 5ms, dom0 100%, target 0%, sent
439Mb/s, dirtied 439Mb/s 67 pages
16:  [2012-03-09 13:37:14 xend 3113] INFO (XendCheckpoint:498) Total pages
sent= 52369 (0.77x)
===========================================================

I understand from the pre-copy algorithm that the last stage involves
stopping the VM and copying the remaining memory pages across to the
destination host.

>From the above excerpt on "line 15" is delta a reflection of the downtime
during this last stop-copy phase?

Looking forward to your responses.


Kind Regards,

Phillip Nkubito




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