[libvirt-users] virtual drive performance

[Thiago Oliveira]

Hi Dominik,

Sure, I beleive you can improve using:

<cpu mode='host-passthrough'>
</cpu>

add io='native'

 <driver name='qemu' type='qcow2' cache='none' io='native'/>

After that, please try again, but I can see other thing, for example,
change the hda=IDE to virtio.

Cheers!

Thiago



2017-06-14 5:26 GMT-03:00 Dominik Psenner <dpsenner at gmail.com>:

> Hi,
>
> I'm investigating a performance issue on a virtualized windows server host
> that is run on a ubuntu machine via libvirt/qemu. While the host can easily
> read/write on the raid drive with 100Mmb/s as observable with dd, the
> virtualized windows server running on that host is barely able to
> read/write with at most 8Mb/s and averages around 1.4Mb/s. This has grown
> to the extent that the virtualized host is often unresponsive and even
> unable to start up its services with system default timeouts. Any help to
> improve the situation is greatly appreciated.
>
> This is the configuration of the virtualized host:
>
> ~$ virsh dumpxml windows-server-2016-x64
> <domain type='kvm' id='1'>
>   <name>windows-server-2016-x64</name>
>   <uuid>XXX</uuid>
>   <memory unit='KiB'>2097152</memory>
>   <currentMemory unit='KiB'>2097152</currentMemory>
>   <vcpu placement='static'>2</vcpu>
>   <resource>
>     <partition>/machine</partition>
>   </resource>
>   <os>
>     <type arch='x86_64' machine='pc-i440fx-xenial'>hvm</type>
>     <boot dev='hd'/>
>   </os>
>   <features>
>     <acpi/>
>     <apic/>
>     <hyperv>
>       <relaxed state='on'/>
>       <vapic state='on'/>
>       <spinlocks state='on' retries='8191'/>
>     </hyperv>
>   </features>
>   <cpu mode='custom' match='exact'>
>     <model fallback='allow'>IvyBridge</model>
>     <topology sockets='1' cores='2' threads='1'/>
>   </cpu>
>   <clock offset='localtime'>
>     <timer name='rtc' tickpolicy='catchup'/>
>     <timer name='pit' tickpolicy='delay'/>
>     <timer name='hpet' present='no'/>
>     <timer name='hypervclock' present='yes'/>
>   </clock>
>   <on_poweroff>destroy</on_poweroff>
>   <on_reboot>restart</on_reboot>
>   <on_crash>restart</on_crash>
>   <pm>
>     <suspend-to-mem enabled='no'/>
>     <suspend-to-disk enabled='no'/>
>   </pm>
>   <devices>
>     <emulator>/usr/bin/kvm-spice</emulator>
>     <disk type='file' device='disk'>
>       <driver name='qemu' type='qcow2' cache='none'/>
>       <source file='/var/data/virtuals/machines/windows-server-2016-x64/
> image.qcow2'/>
>       <backingStore/>
>       <target dev='hda' bus='ide'/>
>       <alias name='ide0-0-0'/>
>       <address type='drive' controller='0' bus='0' target='0' unit='0'/>
>     </disk>
>     <disk type='file' device='cdrom'>
>       <driver name='qemu' type='raw'/>
>       <source file='/var/data/virtuals/machines/windows-server-2016-x64/
> dvd.iso'/>
>       <backingStore/>
>       <target dev='hdb' bus='ide'/>
>       <readonly/>
>       <alias name='ide0-0-1'/>
>       <address type='drive' controller='0' bus='0' target='0' unit='1'/>
>     </disk>
>     <controller type='usb' index='0' model='ich9-ehci1'>
>       <alias name='usb'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x05'
> function='0x7'/>
>     </controller>
>     <controller type='usb' index='0' model='ich9-uhci1'>
>       <alias name='usb'/>
>       <master startport='0'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x05'
> function='0x0' multifunction='on'/>
>     </controller>
>     <controller type='usb' index='0' model='ich9-uhci2'>
>       <alias name='usb'/>
>       <master startport='2'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x05'
> function='0x1'/>
>     </controller>
>     <controller type='usb' index='0' model='ich9-uhci3'>
>       <alias name='usb'/>
>       <master startport='4'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x05'
> function='0x2'/>
>     </controller>
>     <controller type='pci' index='0' model='pci-root'>
>       <alias name='pci.0'/>
>     </controller>
>     <controller type='ide' index='0'>
>       <alias name='ide'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x01'
> function='0x1'/>
>     </controller>
>     <interface type='bridge'>
>       <mac address='52:54:00:0e:f2:23'/>
>       <source bridge='br0'/>
>       <target dev='vnet0'/>
>       <model type='rtl8139'/>
>       <alias name='net0'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x03'
> function='0x0'/>
>     </interface>
>     <serial type='pty'>
>       <source path='/dev/pts/1'/>
>       <target port='0'/>
>       <alias name='serial0'/>
>     </serial>
>     <console type='pty' tty='/dev/pts/1'>
>       <source path='/dev/pts/1'/>
>       <target type='serial' port='0'/>
>       <alias name='serial0'/>
>     </console>
>     <input type='tablet' bus='usb'>
>       <alias name='input0'/>
>     </input>
>     <input type='mouse' bus='ps2'/>
>     <input type='keyboard' bus='ps2'/>
>     <graphics type='vnc' port='5900' autoport='yes' listen='127.0.0.1'>
>       <listen type='address' address='127.0.0.1'/>
>     </graphics>
>     <video>
>       <model type='vga' vram='16384' heads='1'/>
>       <alias name='video0'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x02'
> function='0x0'/>
>     </video>
>     <memballoon model='virtio'>
>       <alias name='balloon0'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x04'
> function='0x0'/>
>     </memballoon>
>   </devices>
>   <seclabel type='dynamic' model='apparmor' relabel='yes'>
>     <label>libvirt-XXX</label>
>     <imagelabel>libvirt-XXX</imagelabel>
>   </seclabel>
> </domain>
>
> Cheers,
> Dominik
>
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