Bug 1017096

Summary: Fail to migrate while the size of migrate-compcache less then 4096
Product: Red Hat Enterprise Linux 7 Reporter: zhenfeng wang <zhwang>
Component: qemu-kvmAssignee: Hai Huang <hhuang>
Status: CLOSED CURRENTRELEASE QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 7.0CC: acathrow, ajia, dyuan, gsun, hhuang, jdenemar, juli, juzhang, michen, mzhan, qzhang, virt-maint, zpeng
Target Milestone: rcKeywords: Reopened
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: qemu-kvm-1.5.3-47.el7 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2014-06-13 10:12:24 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description zhenfeng wang 2013-10-09 09:14:38 UTC 
Description of problem:
Fail to migrate while the size of migrate-compcache less then 4096

Version-Release number of selected component (if applicable):
libvirt-1.1.1-8.el7.x86_64
kernel-3.10.0-33.el7.x86_64
qemu-kvm-rhev-1.5.3-7.el7.x86_64

How reproducible:
100%

Steps
1.Set setenforce 1 && virt_use_nfs 1 (on both source and target)

2.Prepare a guest which the image file is on the NFS server,and mount the nfs server on both source and target
start the guest on the source machine
#virsh start rhelguest1
# virsh list --all
 Id    Name                           State
----------------------------------------------------
 8     rhel7raw                         running

3.Sets size of the cache less than 4096
# virsh migrate-compcache rhel7raw --size  4095
Compression cache: 2.000 KiB
# virsh migrate-compcache rhel7raw
Compression cache: 2.000 KiB


4.Migrate the guest to the target, will fail to migrate the guest to the target
# virsh migrate --live rhel7raw qemu+ssh://xx.xx.xx.xx/system --verbose --compressed
root.xx.xx's password:
error: operation failed: migration job: unexpectedly failed

5.Sets size of the cache more than 4095
 # virsh migrate-compcache rhel7raw --size  4096
Compression cache: 4.000 KiB
# virsh migrate-compcache rhel7raw
Compression cache: 4.000 KiB

6.RE-migrate the guest to the target, will successfully migrate the guest to the target
# virsh migrate --live rhel7raw qemu+ssh://xx.xx.xx.xx/system --verbose --compressed
root.xx.xx's password:
Migration: [100 %]


Actual results:
Fail to migrate the guest to the target while the migrate-compcache less then 4096
Expected results:
If the cache size less then 4096 support the normal migration ,it should be migrated successfully
if not, it should report an proper error, such as fail to migrate ,the cache size should larger than 4095.
Comment 2 Jiri Denemark 2013-10-09 10:09:16 UTC 
Libvirt just calls migrate-set-cache-size with the value provided by a user and QEMU is doing any rounding on that value. It looks like it just doesn't do a good job when the requested size is lower than 4KiB.
Comment 3 Orit Wasserman 2014-02-11 15:37:00 UTC 
*** Bug 1006843 has been marked as a duplicate of this bug. ***
Comment 4 Orit Wasserman 2014-02-12 07:43:41 UTC 

*** This bug has been marked as a duplicate of bug 1006843 ***
Comment 5 Miroslav Rezanina 2014-02-12 12:01:13 UTC 
Fix included in qemu-kvm-1.5.3-47.el7
Comment 7 Qunfang Zhang 2014-02-19 08:21:31 UTC 
Reproduced the issue on qemu-kvm-1.5.3-46.el7.x86_64 and verified pass on qemu-kvm-1.5.3-48.el7.x86_64. 

On the old version qemu-kvm-1.5.3-46.el7.x86_64:

1. Boot up a guest on source host.

(gdb)  r  -cpu SandyBridge -M pc -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -name rhel6.4-64 -uuid 9a0e67ec-f286-d8e7-0548-0c1c9ec93009 -nodefconfig -nodefaults -monitor stdio -rtc base=utc,clock=host,driftfix=slew -no-kvm-pit-reinjection -no-shutdown -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x7 -drive file=/mnt/RHEL-Server-7.0-64-virtio.qcow2,if=none,id=drive-virtio-disk0,format=qcow2,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -drive if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -netdev tap,id=hostnet0,vhost=on -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:d5:51:8a,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=channel1,path=/tmp/helloworld1,server,nowait -device virtserialport,chardev=channel1,name=port1,bus=virtio-serial0.0,id=port1 -chardev socket,id=channel2,path=/tmp/helloworld2,server,nowait -device virtserialport,chardev=channel2,name=port2,bus=virtio-serial0.0,id=port2 -chardev spicevmc,id=charchannel0,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=3,chardev=charchannel0,id=channel0,name=com.redhat.spice.0 -vnc :10 -vga std  -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6 -qmp tcp:0:5555,server,nowait -global PIIX4_PM.disable_s3=0 -global PIIX4_PM.disable_s4=0

2. Boot the guest on destination host with "-incoming tcp:0:5800"

3. Enable xbzrle and set the cache size less than 4096, eg: 4095 byte. And then migrate guest to destination host. 

{"QMP": {"version": {"qemu": {"micro": 3, "minor": 5, "major": 1}, "package": " (qemu-kvm-1.5.3-46.el7)"}, "capabilities": []}}

{"execute":"qmp_capabilities"}
{"return": {}}
{"execute":"migrate-set-capabilities","arguments":{"capabilities":[{"state": true, "capability": "xbzrle"}]}}
{"return": {}}
{"execute":"migrate-set-cache-size","arguments":{"value":4095}}  
{"return": {}}

{"execute": "migrate","arguments":{"uri": "tcp:10.66.4.108:5800"}}
{"return": {}}

{"execute":"query-migrate"}
{"return": {"status": "failed"}}

4. Repeat step 1-3 but with 4096 bytes cache size, this time migration could be finished. 

{"QMP": {"version": {"qemu": {"micro": 3, "minor": 5, "major": 1}, "package": " (qemu-kvm-1.5.3-46.el7)"}, "capabilities": []}}

{"execute":"qmp_capabilities"}
{"return": {}}
{"execute":"migrate-set-capabilities","arguments":{"capabilities":[{"state": true, "capability": "xbzrle"}]}}
{"return": {}}
{"execute":"migrate-set-cache-size","arguments":{"value":4096}}
{"return": {}}
{"execute": "migrate","arguments":{"uri": "tcp:10.66.4.108:5800"}}
{"return": {}}


{"execute":"query-migrate"}
{"return": {"expected-downtime": 30, "xbzrle-cache": {"bytes": 0, "cache-size": 4096, "pages": 0, "overflow": 0, "cache-miss": 0}, "status": "active", "setup-time": 2, "total-time": 5288, "ram": {"total": 4312489984, "remaining": 208711680, "mbps": 268.5668, "transferred": 177928098, "duplicate": 960651, "dirty-pages-rate": 0, "skipped": 0, "normal-bytes": 168951808, "normal": 41248}}}

{"timestamp": {"seconds": 1392797305, "microseconds": 828894}, "event": "STOP"}
{"execute":"query-migrate"}
{"return": {"xbzrle-cache": {"bytes": 0, "cache-size": 4096, "pages": 0, "overflow": 0, "cache-miss": 10}, "status": "completed", "setup-time": 2, "downtime": 72, "total-time": 10381, "ram": {"total": 4312489984, "remaining": 0, "mbps": 268.62512, "transferred": 346380624, "duplicate": 970592, "dirty-pages-rate": 0, "skipped": 0, "normal-bytes": 336986112, "normal": 82272}}}


================
Verified pass on qemu-kvm-1.5.3-48.el7.x86_64, cache size < 4096 bytes is not allowed to be set. 

{"QMP": {"version": {"qemu": {"micro": 3, "minor": 5, "major": 1}, "package": " (qemu-kvm-1.5.3-48.el7)"}, "capabilities": []}}
{"execute":"qmp_capabilities"}
{"return": {}}
{"execute":"migrate-set-capabilities","arguments":{"capabilities":[{"state": true, "capability": "xbzrle"}]}}
{"return": {}}
{"execute":"migrate-set-cache-size","arguments":{"value":4095}}
{"error": {"class": "GenericError", "desc": "Parameter 'cache size' expects is smaller than page size"}}

Re-set cache size to larger than 4095 and re-migrate, succeed. 

So this bug is fixed.
Comment 9 Ludek Smid 2014-06-13 10:12:24 UTC 
This request was resolved in Red Hat Enterprise Linux 7.0.

Contact your manager or support representative in case you have further questions about the request.