[EDITOR] [DirectX 12] Multi-GPU (explicit unbounded)

[ChrisTm]

Hello everyone,

This is probably the stupid question (i don't know). We know today , DirectX 12 , this is probably the end of SLI/Crossfire because DirectX 12 can take advantage of multiple GPUs explicit or explicit unbound (GTX 900 + GTX 800 or GTX + AMD).
But, what about UE4 editor ? Editor can take advantage of multiple GPUs or this will work only at runtime (in the finale game). Have you some info about that ?

Unreal Engine will have this feature ?

Thank

[darthviper107]

The editor can't support that feature. From what I understand, you have to control which elements are assigned to each GPU, and in a game editor those things can vary wildly so it wouldn't work that well.

[SaxonRah]

I can confirm that my R9 270x and GTX 770 both show up in dx12 devices log when DX12 editor is launched, although i have no idea if its using both.

[iniside]

The editor can't support that feature. From what I understand, you have to control which elements are assigned to each GPU, and in a game editor those things can vary wildly so it wouldn't work that well.

I think you understrand it wrong. Though I might it also understrand wrong ;p.

Which CPU render which part of scene is decided without user input (ie, you don't tell, that this specific wall will be rendered on GPU2).
It's "automatically" decided by rendering code, which assigns objects to GPUs based on some abitrary data, set by person who wrote the renderer, or there might be some kind of load balancer in work, which is trying to split rendering work equally between two GPUs (ie, every second mesh rendered on GPU2, or GPU will do pixel shader while GPU2 post processing and vertex shader).

Anyway, at this point I would be happy with directx 12 support which doesn't crash, and then Vulkan, so we can get rid of DirectX 12 ;p.

[darthviper107]

Right, but those things can very between game projects, you might have something with lots of low-poly draw calls, or something with extensive dynamic lighting, or something that depends heavily on particles or whatever, and from what I understand that isn't automatic

[ChrisTm]

Of what i understand , it's Microsoft are working on Ue4/directX 12 , so i don't know, what they are thinking about that , what will they do ? i thinked at something like this : Add some settings in Project>Setting>Mulit-GPU where we can choose, what GPU is used for (If multi-GPU) ex : Render Mesh, Texture = GPU1 , PhisyX , streaming, particles... GPU2 etc...
I hope, we will have some info about that and i hope Epic/Microsoft will do something speciale for we .

For me , i just installed Windows 10 , i will try starting Editor in Dx12 mode and see if my GTX970/660 its using both....
Thank