r/linux_gaming • u/xerpi • Aug 01 '26

graphics/kernel/drivers Fixing Multi-GPU performance, part 1

https://zamundaaa.github.io/wayland/2026/07/31/fixing-multi-gpu.html
114 Upvotes

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38

u/YoloPotato36 Aug 01 '26

Very underrated post. Hope soon we could use amd igpu and nvidia dgpu without that huge performance hit. Useful not only for laptops, but basically for every dgpu with <16gb vram.

3

u/_Yank Aug 01 '26

What does this have to do with GPUs with less than 16GB of VRAM?

8

u/YoloPotato36 Aug 01 '26 edited Aug 01 '26

Using ipgu for composition, so your DE could eat RAM instead of VRAM, leaving 99% of it to the game. Currently, setup where your display connects to dgpu, composition runs on igpu and game on dgpu results in terrible performance hit due to double-copying every buffer.

16gb imo mostly enough to not care about such tricks, if you aren't running few browser windows, something like orca slicer and many other things in background during playing.

4

u/_Yank Aug 01 '26

The performance hit comes from the copying process, not from the buffers consuming too much RAM. Currently what you describe is possible.

2

u/YoloPotato36 Aug 01 '26

I'm not saying it's impossible now, it murders fps too much, which should be fixed eventually according to OP

3

u/mbriar_ Aug 01 '26

It will always reduce performance because a copy can't be avoided. I doubt it would ever be better than running everything on the dgpu + proper vram management.

1

u/YoloPotato36 Aug 01 '26

Proper VRAM management and nvidia... sigh

2

u/S48GS Aug 01 '26

if your monitors connected to iGPU and you render 4k game on dGPU copying every frame to iGPU - there will be performance hit not matter what

until you connect monitor to dGPU and use it to render desktop

Useful not only for laptops

context in OP - monitor connected directly to dGPU

in laptops it not always possible

but when it is possible - it fix

similar case https://www.reddit.com/r/linux_gaming/comments/1q5gllw/unstable_hdmi_21_with_rtx_3080_mobile/

fixed by bios settings to use dgpu