Re: Video Presentation on PCI Express x16 VGA Pass Through to Xen-based Windows XP Home Edition HVM Virtual Machine

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 09/10/09 07:03, Pasi Kärkkäinen wrote:
> On Thu, Sep 10, 2009 at 08:28:03PM +0800, Mr. Teo En Ming (Zhang Enming) wrote:
>   
>> Dear All,
>>
>> Here is my latest video presentation on VGA passthrough. Please check out my
>> blog at http://teo-en-ming-aka-zhang-enming.blogspot.com/ or the Youtube
>> link at http://www.youtube.com/watch?v=1ia3IwG6tp4
>>
>> The "not enough free resources" problem for nVidia Geforce 8400 GS PCI
>> Express x16 graphics card in earlier presentation videos:
>>
>> http://www.youtube.com/watch?v=HNEiSI...<http://www.youtube.com/watch?v=HNEiSInrav0>
>>
>> http://www.youtube.com/watch?v=_hOT_9...<http://www.youtube.com/watch?v=_hOT_9LIG5w>
>>
>> was fixed. Device manager in Windows XP HVM domU no longer shows an
>> exclamation mark besides the nVidia Geforce 8400 GS graphics card. The
>> device is working properly and the resources tab shows the available memory
>> ranges.
>>
>> Full VGA passthrough to Windows XP HVM guest operating system using Xen
>> virtualization has been realized. I am now able to run 3-D video benchmarks
>> on the passed through nVidia GeForce 8400 GS graphics card.
>>
>> All this is possible using Xen 3.5 hypervisor with Intel supplied VGA
>> passthrough patches. Instead of using pvops dom0 kernel 2.6.31-rc6 which
>> causes Win XP domU to run slowly, I am now using pvops dom0 kernel
>> 2.6.30-rc3.
>>
>>     
> Jeremy: Are you aware of any changes after 2.6.30-rc3 that could cause
> this HVM slowness? 
>   

I can't think of anything, unless the new swiotlb code is causing problems.

> Any tips how it could be debugged?
>   

It would help to isolate where the slowness is coming from.  How much
slowdown are we talking about?  Is the HVM domain doing lots of IO at
the time?  Are there any processes using lots of time in dom0?  What's
the interrupt rate like?

    J