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Bug 909038 - Migration downtime is too much more than expected (the value set with migrate_set_downtime command)
Summary: Migration downtime is too much more than expected (the value set with migrate...
Keywords:
Status: CLOSED DUPLICATE of bug 997559
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm
Version: 7.0
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Juan Quintela
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2013-02-08 05:35 UTC by Qunfang Zhang
Modified: 2017-06-07 14:31 UTC (History)
7 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2013-12-18 19:19:40 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Qunfang Zhang 2013-02-08 05:35:28 UTC 
Description of problem:
Set migrate downtime before migration, and the real downtime is too much more.
For example:
Boot a rhel7.0 guest (does not running any application inside, just boot guest up)
(1) Use default 30ms downtime, after migration it's about 535ms.
(qemu) info migrate
capabilities: xbzrle: off 
Migration status: completed
total time: 20860 milliseconds
downtime: 535 milliseconds
transferred ram: 679268 kbytes
remaining ram: 0 kbytes
total ram: 4211072 kbytes
duplicate: 884819 pages
normal: 169601 pages
normal bytes: 678404 kbytes
(qemu) 

(2) Even worse, set downtime as 5s, but the real downtime is more than 40s!
(qemu)migrate_set_downtime 5
after migration:
(qemu) info migrate
capabilities: xbzrle: off 
Migration status: completed
total time: 46591 milliseconds
downtime: 46558 milliseconds
transferred ram: 666185 kbytes
remaining ram: 0 kbytes
total ram: 4211072 kbytes
duplicate: 886438 pages
normal: 166330 pages
normal bytes: 665320 kbytes

I test rhel6.4 host with same command line and image, and set migrate downtime as 5s. The real downtime is much better, about 6~10s. 


Version-Release number of selected component (if applicable):
kernel-3.7.0-0.33.el7.x86_64
qemu-kvm-1.3.0-3.el7.x86_64


How reproducible:
Always

Steps to Reproduce:
1.Boot a guest up
 /usr/libexec/qemu-kvm -M pc -cpu SandyBridge -enable-kvm -m 4G -smp 2,sockets=2,cores=1,threads=1 -enable-kvm -name RHEL7.0 -uuid 94f60faf-1978-4c26-8d9d-a3c5206baa5e -k en-us -rtc base=localtime,clock=host,driftfix=slew -no-kvm-pit-reinjection -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device usb-tablet,id=input0 -drive file=/opt/rhel7.0-64-virtio.qcow2,if=none,id=disk0,format=qcow2,werror=stop,rerror=stop,aio=native -device virtio-blk-pci,bus=pci.0,addr=0x3,drive=disk0,id=disk0 -drive file=/opt/boot.iso,if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,drive=drive-ide0-1-0,bus=ide.1,unit=0,id=cdrom -netdev tap,vhost=on,id=hostnet0 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=44:37:E6:5E:91:5E,bus=pci.0,addr=0x5 -monitor stdio -qmp tcp:0:6666,server,nowait -chardev socket,path=/tmp/isa-serial,server,nowait,id=isa1 -device isa-serial,chardev=isa1,id=isa-serial1 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6 -chardev socket,id=charchannel0,path=/tmp/serial-socket,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm -chardev socket,path=/tmp/foo,server,nowait,id=foo -device virtconsole,chardev=foo,id=console0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7 -vnc :10 -vga std -k en-us -boot c -chardev socket,path=/tmp/qga.sock,server,nowait,id=qga0 -device virtserialport,bus=virtio-serial0.0,chardev=qga0,name=org.qemu.guest_agent.0 -global PIIX4_PM.disable_s3=0 -global PIIX4_PM.disable_s4=0

2. Boot the guest on des host with listening mode.

3. On source host, set migrate downtime as 5s.
(qemu) migrate_set_downtime 5

4. Migrate guest to destination host.
(qemu) migrate -d tcp:$dst_host_ip:5800

5. (qemu)info migrate

  
Actual results:
The real migrate downtime is more than 40s, I repeat ping-pong migration for several times, similar results.

(qemu) info migrate
capabilities: xbzrle: off 
Migration status: completed
total time: 46591 milliseconds
downtime: 46558 milliseconds
transferred ram: 666185 kbytes
remaining ram: 0 kbytes
total ram: 4211072 kbytes
duplicate: 886438 pages
normal: 166330 pages
normal bytes: 665320 kbytes


Expected results:
Migrate downtime should be near to 5s.

Additional info:
Comment 2 Qunfang Zhang 2013-03-04 09:04:49 UTC 
Hi, Juan
Could you give us a suggested acceptable range if the real migration downtime is a little longer than expected downtime we set with command "migrate_set_downtime"?
Then it will be helpful for QE to tell whether the case is pass or fail strictly.

Thanks,
Qunfang
Comment 3 Qunfang Zhang 2013-03-18 09:53:33 UTC 
Seems the migration down time is shorter in qemu-kvm-1.4 than 1.3.

(1) idle guest:
(default downtime)

(qemu) info migrate
capabilities: xbzrle: off 
Migration status: completed
total time: 58365 milliseconds
downtime: 84 milliseconds
transferred ram: 2701724 kbytes
remaining ram: 0 kbytes
total ram: 2113920 kbytes
duplicate: 1360600 pages
normal: 671130 pages
normal bytes: 2684520 kbytes

(2) stressed guest:

(qemu) migrate_set_downtime 4

(qemu) info migrate
capabilities: xbzrle: off 
Migration status: completed
total time: 25355 milliseconds
downtime: 2745 milliseconds
transferred ram: 2067417 kbytes
remaining ram: 0 kbytes
total ram: 2113920 kbytes
duplicate: 61918 pages
normal: 515711 pages
normal bytes: 2062844 kbytes


set downtime as 5s:

(qemu) info migrate
capabilities: xbzrle: off 
Migration status: completed
total time: 26607 milliseconds
downtime: 5524 milliseconds
transferred ram: 2057060 kbytes
remaining ram: 0 kbytes
total ram: 2113920 kbytes
duplicate: 123994 pages
normal: 1685701 pages
normal bytes: 6742804 kbytes

default downtime for a stressed guest:
migration does not finished due to bug 921465.
Comment 4 Qunfang Zhang 2013-03-18 09:54:47 UTC 
(In reply to comment #3)
> Seems the migration down time is shorter in qemu-kvm-1.4 than 1.3.
Host:
[root@localhost ~]# uname -r
3.8.0-0.40.el7.x86_64
[root@localhost ~]# rpm -q qemu-kvm
qemu-kvm-1.4.0-1.el7.x86_64


> 
> (1) idle guest:
> (default downtime)
> 
> (qemu) info migrate
> capabilities: xbzrle: off 
> Migration status: completed
> total time: 58365 milliseconds
> downtime: 84 milliseconds
> transferred ram: 2701724 kbytes
> remaining ram: 0 kbytes
> total ram: 2113920 kbytes
> duplicate: 1360600 pages
> normal: 671130 pages
> normal bytes: 2684520 kbytes
> 
> (2) stressed guest:
> 
> (qemu) migrate_set_downtime 4
> 
> (qemu) info migrate
> capabilities: xbzrle: off 
> Migration status: completed
> total time: 25355 milliseconds
> downtime: 2745 milliseconds
> transferred ram: 2067417 kbytes
> remaining ram: 0 kbytes
> total ram: 2113920 kbytes
> duplicate: 61918 pages
> normal: 515711 pages
> normal bytes: 2062844 kbytes
> 
> 
> set downtime as 5s:
> 
> (qemu) info migrate
> capabilities: xbzrle: off 
> Migration status: completed
> total time: 26607 milliseconds
> downtime: 5524 milliseconds
> transferred ram: 2057060 kbytes
> remaining ram: 0 kbytes
> total ram: 2113920 kbytes
> duplicate: 123994 pages
> normal: 1685701 pages
> normal bytes: 6742804 kbytes
> 
> default downtime for a stressed guest:
> migration does not finished due to bug 921465.
Comment 5 Hai Huang 2013-12-18 19:19:40 UTC 

*** This bug has been marked as a duplicate of bug 997559 ***
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