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Re: [Xen-devel] Question about VirtIO on Xen - Disk performance issues



Hi,
Thanks for the hints , I did experiment with the changes you suggested and now we were able to achieve the following result : the performance of the domU is 50 % of the dom0 .

Is it possible to improve these numbers more ?

Also , do you have any advice on where to find extensive documentation on how to use Xen ?


Thank you

Luca

Il 05/01/2016 15:05, Stefano Stabellini ha scritto:
There are a few issues in the config files. In conf_DomU_WindowsHVM:

- device_model is set to /usr/lib64/xen/bin/qemu-dm, which is the old
  qemu-xen-traditional device model, known to have worse disk
  performance. Just delete this line to use the newer QEMU based tree.
- disk is set to [ '/dev/vg0/winvirtio,raw,xvda1,rw' ], but you cannot
  expose only a partition of a disk to a Windows HVM domain. The correct
  disk line would be: disk = [ '/dev/vg0/winvirtio,raw,hda,rw' ]

In conf_DomU_Xen:

- you are missing builder="hvm", which means you are using a PV guest
  rather than an HVM guest. PV guests tends to be slower on new
  hardware.

What version of Xen are you using?


On Tue, 5 Jan 2016, Luca Tongiani wrote:
Sorry but I sent these logs because I have no longer available the Virtualizer of Windows DomU .
In any case the problem of the performance of disks is present both in the case of Linux machines PV and Windows
machines HVM .
I attach the complete log of the server and the conf of my HVM Windows Machine.

Thanks again


Il 05/01/2016 13:42, Stefano Stabellini ha scritto:

The xenstore-ls output is not complete. Could you please send it again?

I noticed from the DomU config file that it is not a Windows VM, as
previously discussed, but a Linux VM. That is OK, but of course in that
case you won't be able to use the Windows PV drivers which I linked.
Linux has its own set of drivers. Did you enable the Xen PV frontends in
the Linux kernel you use (/var/xen/boot/vmlinuz-4.0.5-gentoo_bmsbackup)?
Did you compile them a built-in or as modules?

On Tue, 5 Jan 2016, Luca Tongiani wrote:

Hi,
thanks in advance for your reply :)


I have attached the following email configuration DomU and the output you have requested .
Performance disk are all my machines the most serious problem , even if they are used powerful hardware .
Differences in Disk writing in DomU are 1/3 of those of the Dom0 .


Thank you in advance Luca







Il 05/01/2016 12:09, Stefano Stabellini ha scritto:

Could you please post your VM config file and the output of
xenstore-ls once the VM has completed the boot sequence?

On Tue, 5 Jan 2016, Luca Tongiani wrote:

Hi Stefano,
im writing to you because im having issue with I/O disk in my DomU With Xen (Gentoo based system).

I tried to use the driver that you provided for the PV .
But the results are still not good , there is no way to support the use of Xen VirtIO disk ? Many thanks in
advance

Luca

Il 12/16/15 12:31, Stefano Stabellini ha scritto:

Hello Luca,

the recommended way to increase disk performance would be to use Xen PV
disks. You just need to install the Windows PV drivers:

http://www.xenproject.org/developers/teams/windows-pv-drivers.html

But using VirtIO disk should also increase performance, even though
most probably not as much.

Cheers,

Stefano

On Tue, 15 Dec 2015, Luca Tongiani wrote:

Hi to all,
I'm writing you this mail for asking some advice about a great problem i'm havin in running a Windows VM
(HVM) onto a Xen (Gentoo based) Hypevisor.

I need to achieve maximum performance from this VM because of intense SQL tasks running in it.

I've seen good improvement in IO on disk using VirtIO on a Windows VM onto a QEMU (QNAP) hypervisor, and i'm
tryin to use this feature also on my Xen HV.
Is VirtIO disk a good way to improve performance?

Thx in advance and hope to keep in touch
--

Luca Tongiani

Sinte srl
Soluzioni Informatiche e Telematiche
via Monte Grappa 4/B
20900 Monza (MB)

Cel (+39) 339 745 49 21
Tel (+39) 039 200 59 60
Fax (+39) 039 200 69 42
Web www.sinte.net




--

Luca Tongiani

Sinte srl
Soluzioni Informatiche e Telematiche
via Monte Grappa 4/B
20900 Monza (MB)

Tel (+39) 039 200 59 60
Fax (+39) 039 200 69 42
Web www.sinte.net




--

Luca Tongiani

Sinte srl
Soluzioni Informatiche e Telematiche
via Monte Grappa 4/B
20900 Monza (MB)

Tel (+39) 039 200 59 60
Fax (+39) 039 200 69 42
Web www.sinte.net




--

Luca Tongiani

Sinte srl
Soluzioni Informatiche e Telematiche
via Monte Grappa 4/B
20900 Monza (MB)

Tel (+39) 039 200 59 60
Fax (+39) 039 200 69 42
Web www.sinte.net




--

Luca Tongiani

Sinte srl
Soluzioni Informatiche e Telematiche
via Monte Grappa 4/B
20900 Monza (MB)

Tel (+39) 039 200 59 60
Fax (+39) 039 200 69 42
Web www.sinte.net

Attachment: luca_tongiani.vcf
Description: Vcard

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