As you can guess i am pretty new to KVM.
Here is what i have found:
/usr/bin/kvm -S -M pc-0.12 -enable-kvm -m 2048 -smp
1,sockets=1,cores=1,threads=1 -name linbrotestNC -uuid
5cd17775-c826-7422-6634-428876225868 -nodefaults -chardev
socket,id=monitor,path=/var/lib/libvirt/qemu/linbrotestNC.monitor,server,nowait
-mon chardev=monitor,mode=readline -rtc base=utc -boot nc -drive
file=/dev/vg/lin01-root,if=none,id=drive-virtio-disk0,boot=on,format=raw,cache=none
-device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0
-drive file=/dev/vg/lin01-swap,if=none,id=drive-virtio-disk1,format=raw,cache=none
-device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk1,id=virtio-disk1
-device virtio-net-pci,vlan=0,id=net0,mac=52:54:00:5a:92:58,bus=pci.0,addr=0x3
-net tap,fd=47,vlan=0,name=hostnet0 -chardev pty,id=serial0 -device
isa-serial,chardev=serial0 -usb -vnc 127.0.0.1:1 -k en-us -vga cirrus
-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6
(got this info from ps, but is there a better place to find the kvm
command line ?. I created the vm with virt-manager, but if you tell it
is better to use virt-inst ... will do so.)
As you can see i use lvm block devices with virtio enabled.
I have read some doc about the "cache=none" and here my machine is using it.
Here is the definition of my disk in my machine xml file:
<devices>
<emulator>/usr/bin/kvm</emulator>
<disk type='block' device='disk'>
<driver name='qemu' type='raw' cache='none'/>
<source dev='/dev/vg/lin01-root'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04'
function='0x0'/>
</disk>
Thank you.
Benoit.
On Thu, Oct 13, 2011 at 11:19 AM, Michael Tokarev <mjt@xxxxxxxxxx> wrote:
> On 13.10.2011 13:05, benoit ROUSSELLE wrote:
>> Hello,
>>
>> Can someone running with virtio tell me if this is normal to have such
>> a difference with dd between host and guest machine ?
>> host dd is 500MB/s
>> guest dd is 150MB/s
>>
>> All other questions are optionnal for now :D
>
> Well, one question is mandatory: what is your kvm command line?
> Without it, there's no way to answer any other questions.
>
> /mjt
>
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