Run multiple instances on multiple displays

Development Rendering
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Steps to Reproduce
I have a problem with multiple instances on multiple monitors on Linux and hope you can help me.

This is my setup.

- Two identical NVIDIA GPUs (0,1)

- One monitor connected to each GPU (0,1)

- I want to start two instances of my game

- Instance A should run on GPU 0 and be displayed on monitor 0

- Instance B should run on GPU 1 and be displayed on monitor 1

With the vkcube I got the whole thing working as follows.

xorg.conf with two XScreens (attached)

Start vkcubes:

DISPLAY=:1.0 vkcube --gpu_number 0

DISPLAY=:1.1 vkcube --gpu_number 1

I tried the same with my game.

DISPLAY=:1.0 ./MyGame -ini:Engine:[/Script/Engine.RendererSettings]:r.GraphicsAdapter=0

DISPLAY=:1.1 ./MyGame -ini:Engine:[/Script/Engine.RendererSettings]:r.GraphicsAdapter=1

Everything works on Monitor 0 and GPU 0. On Monitor1 on GPU1 I get this error:

“Cannot find a compatible Vulkan device that supports surface presentation.”

My Game is just an empty project from 5.6.1

Do you have any idea what I am doing wrong and how I can create my desired behavior?

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Hi Malte,

Can you provide a fill application log for the UE instance running on graphics adapter 1 where it fails to find a compatible VK device supporting surface presentation?

Best regards.

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Hi Stéphan,

thank you for your answer.

Here is the logfile.

Regards,

Malte

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Hi Malte,

Are you able to share the output of VulkanInfo, just to see how Vulkan detects the hardware (make sure lavapipe isn’t GraphicAdapter 1 or something of the sort, as vkcubes car run under lavapipe but UE cannot).

Best regards.

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Hi Malte,

Just wanted to follow up. We have tested multiple instances of UE on a multi GPU Ubuntu setup and it seems to work as expected. When letting Unreal pick the GPU, it will skip “software devices” (CPU drivers), however, when you force the index, it will use it regardless of its type. Ubuntu installs the lavapipe device by default… So it’s important to run VulkanInfo and pull the right indices for the physical GPUs you want to assign as the software drivers are not supported by UE as they are by vkcube. If the issue persists, don’t hesitate to reach out again.

Best regards.

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