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Re: [Xen-devel] [Xen-users] GPU Pass Through Comment - DomU GPU Performance Regression after Reboot - Workaround

On Feb 24, 2012 5:17 PM, "Tobias Geiger" <tobias.geiger@xxxxxxxxx> wrote:
> Hi!
> after the first disappointment about the FirePro-Driver not solving my issue, i
> fiddled around with this problem and finally found a solution which solves the
> Performance-Regression i'm experiencing in my setup;
> The Problem is: GPU Performance degrades to about 10% after a DomU Reboot (GPU
> is ATI, but this also happend with a NVIDIA iirc , so no ATI-specific Problem).
> The Workaround: too easy :) Simply "Eject" the GPU after Windows has booted -
> the screen goes black, it re-initializes the Card and re-attaches after a few
> seconds. From then on Performance is back to normal.
> Ejecting is done via the little Device-Manager Icon in the Taskbar (this one:
> http://www.technipages.com/wp-content/uploads/2011/01/Windows-7-Remove-
> Hardware-option.pngwww.technipages.com/wp-content/uploads/2011/01/Windows-7-
> Remove-Hardware-option.png )
> To Automate this, i used a little tool called "DevEject" from heise.de - it's
> "OpenSource" Licensed and works even in Win7-64:
> ftp://ftp.heise.de/pub/ct/listings/0316-208.zip
> There may be other Tools/Scripting solutions via WSH/Powershell/VBS/CMD/...
> Greetings!
> Tobias

Thanks for sharing! Glad you found a simple workaround.

That said, I still think it's the 'fault' of... uh, something in dom0. Maybe the backend that actually handled the booting of the Windows domU needs to relinquish its grip... or maybe it sent the signal of 'device eject' too early, so the Windows subsystem is not yet ready...

... or maybe Windows itself sucks :-P

Anyways, I am not currently using GPU pass-through, but your explanation (and the fine tool you linked to)Â definitely will go into my personal KnowledgeBase :-)


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