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Re: [Qemu-devel] windows guest virtio serial and balloon driver test iss

From: Cao,Bing Bu
Subject: Re: [Qemu-devel] windows guest virtio serial and balloon driver test issues
Date: Mon, 05 Dec 2011 10:44:55 +0800
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On 11/29/2011 08:36 PM, Vadim Rozenfeld wrote:
On Tue, 2011-11-29 at 08:58 +0800, Cao,Bing Bu wrote:

      Rozenfeld,Thanks,got it!

      And do you know whether there are some sufficient test tools (such
as IOmeter)
      to test the virtio driver performance?
IoMeter is good. But you also might be interested in
SQLIOSim, database hammer, and diskio (part of WLK) + xperf.

On 11/25/2011 02:42 PM, Vadim Rozenfeld wrote:
On Fri, 2011-11-25 at 09:59 +0800, Cao,Bing Bu wrote:

Thanks,Frenkel.The test application of the balloon must be run as

But I found 2 problems(question) this week when testing windows guest

      If only virtio serial driver installed,the virtio serial test app
can not enumerate/find the virtio serial device,
      but after virtio balloon driver installed,the app can find the
virtio serial device correctly.
      Because of the same GUID which balloon and serial both use?
Correct. This test application is a very simplified one. We published it
mostly as an example, but not as a real test application. It doesn't
enumerate all virtio serial instances, rather just find the
first one and use it.

      When inflate/deflate the balloon size using qemu monitor balloon
      the total physical memory did not decrease/increase
correspondingly,as seen from "resource monitor",
      only the "available memory" size descrease/increase.But I test on
other Linux guest,
      the total physical memory of the guest OS was changed.

      Is it a problem? If not,is it confusing to user?
      Related to the windows internal memory management?

Total physical memory on Windows will always be the same,
because we don't hot-plug/unplug physical memory.
Balloon driver works with non-paged pool memory instead.
So, every time you inflate or deflate balloon in your system,
you should see "Available memory" is changing, while physical
will always be the same.


On 11/21/2011 06:33 PM, Arkady Frenkel wrote:
On 11/21/2011 10:39 AM, Cao,Bing Bu wrote:

      Recently,I am testing windows guest driver on Win7 and
WinXP(32bit) with the latest windows guest driver development source.
      Download from

      It seems OK both on Win7 and WinXP,the r/w performance is better
than IDE disk.

      I tried to test virtio serial driver using the test application in
the project.

      Write: OK
      Read: Error: Read File Failed.

      The test application return error "can not find vioserial device".
      But i debug the code and check that the GetDevicePath() return
value is not NULL,and same as the value when testing on WinXP.
      Why the CreateFile() in init() not called? (:


      QEMU monitor: device_add virtio-balloon-pci

      On the guest,a new device "PCI standard RAM controller" added.
      But the Device Manager prompt "No driver installed for this
device", but install the driver "balloon.sys" failed.
      It said the driver is up to date.    Confused. (:

      How can I install and test the balloon driver on Windows?

The kvm-guest-drivers-windows.git on kernel.org is not available,is
there any mirror git repository?
Any mail-list or bugzilla for windows guest driver?

Any help from will be appreciated.

You need to run serial test app as admin only.

To install balloon you have to go throw additional option when click on
"Browse my computer for driver software". Choose "Let me pick from the
list of device drivers on my computer" option.


Best regards
Cao,Bing Bu

Thanks you,Vadim.(:

Is there anything TO-DO or need further optimization in current windows guest driver? How could I contribute to the windows guest driver development(test patches,sign-off patches,bug fix,etc.)?

Best Regards,
Cao,Bing Bu

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