[Bug 524447] Re: virsh save is very slow

[dum8d0g]

Using ubuntu natty narwhal installed today (2011-03-24) I tried to do a
snapshot with the help of libvirt. Here are the results using natty
version of qemu-kvm and libvirt and using presented slowdown packages.

root at koberec:~# time virsh snapshot-create 1
Domain snapshot 1300968929 created

real    4m39.594s
user    0m0.000s
sys     0m0.020s
root at koberec:~# cd /storage/slowsave/
root at koberec:/storage/slowsave# dpkg -l | grep -E 'libvirt|qemu'                                                                                                                                                 
ii  libvirt-bin                     0.8.8-1ubuntu5                           the programs for the libvirt library
ii  libvirt0                        0.8.8-1ubuntu5                           library for interfacing with different virtualization systems
ii  qemu-common                     0.14.0+noroms-0ubuntu3                   qemu common functionality (bios, documentation, etc)
ii  qemu-kvm                        0.14.0+noroms-0ubuntu3                   Full virtualization on i386 and amd64 hardware
root at koberec:/storage/slowsave# dpkg -r qemu-common qemu-kvm                                                                                                                                                     
root at koberec:/storage/slowsave# dpkg -i qemu-common_0.12.5+noroms-0ubuntu7.2_all.deb qemu-kvm_0.12.5+noroms-0ubuntu7.2_amd64.deb 
root at koberec:/storage/slowsave# pkill kvm; sleep 5; service libvirt-bin restart
root at koberec:/storage/slowsave# time virsh snapshot-create 1
Domain snapshot 1300969754 created

real    2m22.055s
user    0m0.000s
sys     0m0.010s
root at koberec:/storage/slowsave# qemu-img snapshot -l /storage/debian.qcow2 | tail -n 1
8         1300969754              57M 2011-03-24 08:29:14   00:03:37.652
root at koberec:/storage/slowsave# virsh console 1
Connected to domain vm
Escape character is ^]

Debian GNU/Linux 5.0 debian ttyS0

debian login: root
Password: 
Last login: Thu Mar 24 08:15:18 EDT 2011 on ttyS0
Linux debian 2.6.26-2-amd64 #1 SMP Thu Sep 16 15:56:38 UTC 2010 x86_64

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
debian:~# free -m
             total       used       free     shared    buffers     cached
Mem:           561         39        521          0          4         16
-/+ buffers/cache:         19        542
Swap:          478          0        478
debian:~# 
root at koberec:/storage/slowsave# dd if=/dev/urandom of=/storage/emptyfile bs=1M count=40
40+0 records in
40+0 records out
41943040 bytes (42 MB) copied, 5.4184 s, 7.7 MB/s


I am not sure if my measurements are relevant to anything in here, but I hope so.

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https://bugs.launchpad.net/bugs/524447

Title:
  virsh save is very slow