Help wanted: AMD & Nvidia Hybrid shenanigans on Linux

Hardware gtx1080 rx580 i7-5930K asus rampage V
Software Arch linux KDE mesa

Observation:

The gtx1080 runs games much better as expected but when attempting to play games on a 4K monitor and do anything else on another at the same time the Nvidia GPU can not manage and AMD can.

So i would like to ask if anyone here knows a way to run the desktop on the AMD GPU while running games on Nvidia or something similar.
(I did attempt to enable IOMMU but messed up somewhere)

well you have a few options here. You could easily do a windows virtual machine. It looks like you have all the necessary hardware. Or you could look into setting up nvidia-xrun

I’m assuming there’s a good way to run/mirror a tty inside a DE?
(or seprate ttys for seprate monitors?)
because otherwise I’m not sure how this would allow me to run just my games on the nvidia gpu but other non game related things on the amd one.

Since if i understand right,
This allows 2 open desktops one on each GPU.
and i can only have one of them displayed at once
which would mean that the performance issue with nvidia would persist?
(use case e.g. here is playing a game and watching a video)

Xrun was designed to replace bumblebee. these projects were intended to be used with optimus laptops however they can be implemented to your use case as well.

That does clear things up a bit, thanks.
Will try to use it
I noticed you have similar hardware GPU wise
What’s your setup regarding this?

Also the arch wiki page on xrun uses the proprietary driver, does this work with the open source one?

I actually recently swapped my 1070 for a vega 56, however I use my beefier GPU in a passthrough VM. sometimes I’ll play games in linux with my 580 though. I know about xrun because of a friend who has an optimus laptop. He wanted to play MHW but bumblebee is old and doesn’t work with vulkan. He mostly figured it out on his own so I wouldn’t be much help in setting it up I’m afraid.

is pci passthrough a thing that must be done at boot or could you use your vega card on linux with relative ease?
(As in if you wanted to play something more demanding on linux would it be difficult to use the vega card? would it require a reboot, restarting xorg?)

It is possible to do that. It’s definitely easier with an nvidia card so you’ve got that going for you. and if you use xrun to handle the games still it actually should make the process really seamless for you… I think. In the case of my vega card specifically there is a known bug that requires using one of various workarounds. I’m currently using the simplest one which is putting my system to sleep before starting the VM. it is still possible for me but I don’t bother with using my VM gpu in the host system ever.

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