[one-users] virtio-blk-data-plane and x-data-plane=on

[Valentin Bud]

Hi Erico,

This is the first time I hear about virtio-blk-data-plane. Thank you for
the info, looks like this feature brings notable IO improvements.

You can try to use the RAW Section [1] to pass special attributes to the
underlying hypervisor.
I have found a blog post [2] in which there is a method to enable
virtio-blk-data-plane using the libvirt XML. The RAW section DATA gets
passed to libvirt in XML format.

I think the following could work:

RAW = [
  TYPE="kvm",
  DATA="<qemu:commandline><qemu:arg value='-set'/><qemu:arg
value='device.virtio-disk0.scsi=off'/></qemu:commandline><!--
config-wce=off is not needed in RHEL 6.4 --><qemu:commandline><qemu:arg
value='-set'/><qemu:arg
value='device.virtio-disk0.config-wce=off'/></qemu:commandline><qemu:commandline<qemu:arg
value='-set'/><qemu:arg
value='device.virtio-disk0.x-data-plane=on'></qemu:commandline>"
]

I don't have a test machine around and I would to hear back from you if it
works or not.

[1]: http://opennebula.org/documentation:rel4.2:template#raw_section
[2]:
http://blog.vmsplice.net/2013/03/new-in-qemu-14-high-performance-virtio.html

Health and Goodwill,


On Sat, Aug 31, 2013 at 11:01 PM, Erico Augusto Cavalcanti Guedes <
eacg at cin.ufpe.br> wrote:

> Hello,
>
> on [1], page 10, section 2.3 - KVM Configuration: "To achieve the best
> possible I/O rates for the KVM guest, the virtio-blk-data-plane feature was
> enabled for each LUN (a disk or partition) that was passed from the host to
> the guest. To enable virtio-blk-data-plane for a LUN being passed to the
> guest, the x-data-plane=on option was added for that LUN in the qemu-kvm
> command line used to set up the guest. For example:
> /usr/libexec/qemu-kvm -drive
> if=none,id=drive0,cache=none,aio=native,format=raw,file=<disk or partition>
> -device virtio-blk-pci,drive=drive0,scsi=off,x-data-plane=on
> "
> I'll be grateful if you can help me with the following question:
> How to customize -device virtio-blk-pci parameter during OpenNebula VM
> initialization to insert x-data-plane=on on it?
>
> My VM Template:
> CONTEXT=[NETWORK="YES",SSH_PUBLIC_KEY="$USER[SSH_PUBLIC_KEY]"]
> CPU="1"
>
> DISK=[AIO="native",BUS="virtio",CACHE="none",DEV_PREFIX="vd",FORMAT="raw",IMAGE_ID="1"]
> GRAPHICS=[LISTEN="0.0.0.0",TYPE="VNC"]
> MEMORY="256"
> NIC=[NETWORK_ID="0"]
> OS=[ARCH="i686",BOOT="hd"]
>
> KVM process on node:
> /usr/bin/kvm -S -M pc-i440fx-1.6 -cpu qemu32 -enable-kvm -m 256 -smp
> 1,sockets=1,cores=1,threads=1 -name one-27
> -uuid c014337c-5255-e983-862e-b744f889aa49 -no-user-config -nodefaults
> -chardev
> socket,id=charmonitor,path=/var/lib/libvirt/qemu/one-27.monitor,server,nowait
> -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc
> -no-shutdown-boot c
> -drive
> file=/srv/cloud/one/var//datastores/0/27/disk.0,if=none,id=drive-virtio-disk0,format=raw,cache=none
> -device
> virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0
> -drive
> file=/srv/cloud/one/var//datastores/0/27/disk.1,if=none,media=cdrom,id=drive-ide0-0-0,readonly=on,format=raw
> -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0
> -netdev tap,fd=22,id=hostnet0
> -device
> virtio-net-pci,netdev=hostnet0,id=net0,mac=02:00:c0:a8:0f:6e,bus=pci.0,addr=0x3
> -usb -vnc 0.0.0.0:27 -vga cirrus -device
> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
>
> I'm running ONE 4.2 on Debian 7.1 x86_64, kernel 3.2.0-4-amd64, with
> customized qemu-1.6(compiled by myself to support virtio-blk-data-plane) to
> enable virtio-blk-data-plane, with Debian 7.1 i386 VMs.
>
> Thanks in advance,
>
> Erico.
>
> [1]
> ftp://public.dhe.ibm.com/linux/pdfs/KVM_Virtualized_IO_Performance_Paper_v2.pdf
>
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>
>


-- 
Valentin Bud
http://databus.pro | valentin at databus.pro
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