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

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

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
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> 
> 
> 
> 
> --
> 
> 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
> 
> 
> 

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