[libvirt-users] Sluggish performance with virtio and Win10

John Obaterspok john.obaterspok at gmail.com
Thu Feb 18 11:59:52 UTC 2016

2016-02-18 11:25 GMT+01:00 Martin Kletzander <mkletzan at redhat.com>:

> On Thu, Feb 18, 2016 at 10:41:42AM +0100, John Obaterspok wrote:
>> 2016-02-18 10:13 GMT+01:00 Martin Kletzander <mkletzan at redhat.com>:
>> On Thu, Feb 18, 2016 at 08:49:38AM +0100, John Obaterspok wrote:
>>> Hello,
>>>> I'm using virt-manager on my F23 box to run a Windows 10 image but the
>>>> performance is so bad it's killing me.
>>>> I have "vmx" flag in /proc/cpuinfo
>>>> # lsmod |grep kvm
>>>> kvm_intel             167936  6
>>>> kvm                   503808  1 kvm_intel
>>>> virtio-win-0.1.112-1.noarch
>>>> But no virtio modules loaded. Should they be loaded nowadays?
>>> Not on the host AFAIK.
>>> The disk format used is vmdk with no caching and native mode.
>>>> The io is 100% in windows task manager performing less than 1MB/s
>>>> Any clues?
>>>> What are the figures from the host?  What is qemu doing and what are the
>>> other processes and devices doing?
>>> What is the best way to find this out?
> {,a,h}top should do for the initial runs, just to see if the block layer
> is busy or the CPU is busy or something else is blocking it
atop seems to indicate that sdd is busy?

DSK |          sdd |  busy     96% |              |  read    1455 | write
1319 |  KiB/r      5 | KiB/w      9 |               | MBr/s   0.74 | MBw/s
  1.26  | avq     1.01 |               | avio 3.43 ms |

# mount | grep sdd
/dev/sdd2 on /vm type ext4 (rw,relatime,seclabel,data=ordered)

guest configuration is below:

<domain type='kvm'>
  <memory unit='KiB'>4194304</memory>
  <currentMemory unit='KiB'>4194304</currentMemory>
  <vcpu placement='static'>4</vcpu>
    <type arch='x86_64' machine='pc-i440fx-2.4'>hvm</type>
      <relaxed state='on'/>
      <vapic state='on'/>
      <spinlocks state='on' retries='8191'/>
      <hidden state='on'/>
    <vmport state='off'/>
  <cpu mode='host-model'>
    <model fallback='allow'/>
  <clock offset='localtime'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
    <timer name='hypervclock' present='yes'/>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='no'/>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/usr/share/virtio-win/virtio-win.iso'/>
      <target dev='hda' bus='ide'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    <disk type='file' device='disk'>
      <driver name='qemu' type='vmdk' cache='none' io='native'/>
      <source file='/vm/storage/win10-box.img'/>
      <target dev='vda' bus='virtio'/>
      <boot order='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x0a'
    <controller type='usb' index='0' model='ich9-ehci1'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06'
    <controller type='usb' index='0' model='ich9-uhci1'>
      <master startport='0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06'
function='0x0' multifunction='on'/>
    <controller type='usb' index='0' model='ich9-uhci2'>
      <master startport='2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06'
    <controller type='usb' index='0' model='ich9-uhci3'>
      <master startport='4'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06'
    <controller type='pci' index='0' model='pci-root'/>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01'
    <controller type='virtio-serial' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05'
    <controller type='sata' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x08'
    <interface type='direct'>
      <mac address='52:54:00:cc:f0:31'/>
      <source dev='eno1' mode='bridge'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03'
    <serial type='pty'>
      <target port='0'/>
    <console type='pty'>
      <target type='serial' port='0'/>
    <input type='tablet' bus='usb'/>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='spice' autoport='yes'/>
    <sound model='ich6'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04'
      <model type='vga' vram='16384' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02'
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07'
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