[fedora-virt] virtio block driver performance versus ide

[Paul Lambert]

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 at 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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