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Re: [fedora-virt] virtio block driver performance versus ide



I will second this performance observation.  After the latest round of pathces, I too found that my Windows XP VM was performing much faster than before and consuming much less cpu time.  I then observed that my Fe-11 VM was performing considerably slower.  Sure enough, I have checked my hda for each VM and the Windows was using native IDE and FE-11 was using virtio.  I have now changed my FE-11 hda to IDE.  Seems to exhibit much more pep!  So much for paravirtualization. 

Paul

On Thu, Oct 15, 2009 at 3:50 PM, Dale Bewley <dlbewley lib ucdavis edu> wrote:
I assumed the virtio block driver to be faster for a kvm guest than ide,
but I'm seeing quite the opposite. Is this expected?

I normally create guests with a wrapper script around virt-install which
creates guests configured to use IDE disks:

f11-db1.xml-    <emulator>/usr/bin/qemu-kvm</emulator>
f11-db1.xml:    <disk type='file' device='disk'>
f11-db1.xml-      <source file='/var/lib/libvirt/images//f11-db1.img'/>
f11-db1.xml-      <target dev='hda' bus='ide'/>
f11-db1.xml:    </disk>

I am currently creating a guest with the virt-manager wizard which
apparently uses virtio by default:

f11-archivist.xml-    <emulator>/usr/bin/qemu-kvm</emulator>
f11-archivist.xml:    <disk type='file' device='disk'>
f11-archivist.xml-      <source
file='/var/lib/libvirt/images//f11-archivist.img'/>
f11-archivist.xml-      <target dev='vda' bus='virtio'/>
f11-archivist.xml:    </disk>

The filesystem formatting and installation are going very very slowly.

Host is 2.6.29.6-213.fc11.x86_64 4x quad core. Guests are also fc11
x86_64.

BTW, I've updated to virt-manager-0.7.0-7, libvirt-0.6.2-18,
qemu-kvm-0.10.6-6, and kernel-2.6.30.8-64 just before creating this
guest but have not restarted libvirtd or rebooted the host.

--
Dale Bewley - Unix Administrator - Shields Library - UC Davis
GPG: 0xB098A0F3 0D5A 9AEB 43F4 F84C 7EFD  1753 064D 2583 B098 A0F3

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