[vfio-users] VGA Passthrough limitations?

[Quentin Deldycke]

Easy to see, dmesg and you should have plently of flood about it :)

--
Deldycke Quentin


On 18 May 2016 at 16:39, thibaut noah <thibaut.noah at gmail.com> wrote:

> I'm thinking same thing as heroes of the storm, msrs spamming ?
>
> 2016-05-18 14:27 GMT+02:00 Andrei Grigore <andrei.grg at gmail.com>:
>
>> Dear all,
>>
>> I have this very strange issue that I can not understand:
>>
>> Everything works flawlessly or even better than bare metal. ...thing is,
>> if I enable stereoscopic 3d vision (nvidia) in game, the performance drops
>> to unplayable. The reason for that are CPU /RAM intensive elements such as
>> view distances. Dropping other graphical elements to the lowest possible
>> value makes no difference. This means that the GPU is not the bottleneck.
>> Tested this on bare metal and i get around 50 fps with everything maxed
>> out. With VGA passthrough I barely get 20. Disabling 3d vision boosts
>> everything to 60 fps.
>>
>> The entire 3d vision sensor usb bus is passed through as well. I am
>> running just this VM with 8/8 cores of a fx-8230 cpu with 12 gb of ram. The
>> cpu is passed with host-passthrough. I am even using your latest patch and
>> had enabled hyperv extensions with nvidia GPUs.
>>
>> The VM is installed clean with nothing but the games in it. As said using
>> the same drivers on a bare metal windows works flawlessly.
>>
>> I cannot understand where the bottleneck is. CPU usage is not even close
>> to 100%, plenty of ram left and not even 1MB of swap is made.
>>
>> I don't even know where to seek the problem. What can cause such a
>> massive fps drop? Is there any bandtwidth limit that caps the 2x rendering
>> needed for 3d vision?
>>
>> Many thanks,
>> Andrei.
>>
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>>
>>
>
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