DirectX® 12 for Enthusiasts: Explicit Multiadapter

[andybird123]

I could see AMD potentially implementing support for that sort of thing in their drivers but Nvidia would never allow it. Currently their drivers prevent running an AMD card alongside a Nvidia card.

No they don't, they prevent nvidia GPU running physx alongside an AMD card as primary. If multiadapter is a requirement of DX12 then they have no choice or their cards wont be DX12 compliant.

I would imagine they would be able to retain control of nvidia specific addons, but I don't think they are going to get a choice over multiadaptor itself.

 

[tommybhoy]

No they don't, they prevent nvidia GPU running physx alongside an AMD card as primary present in the system regardless primary/secondary etc. If multiadapter is a requirement of DX12 then they have no choice or their cards wont be DX12 compliant.

I would imagine they would be able to retain control of nvidia specific addons, but I don't think they are going to get a choice over multiadaptor itself.

 

[Mauller]

No they don't, they prevent nvidia GPU running physx alongside an AMD card as primary. If multiadapter is a requirement of DX12 then they have no choice or their cards wont be DX12 compliant.

I would imagine they would be able to retain control of nvidia specific addons, but I don't think they are going to get a choice over multiadaptor itself.

Multi adapter is not a requirement of directx 12, nor is mixed mode multi gpu.

Explicit control over the GPU can allow different gpu's to be used in a system but it is up to the developer to write support for it.

Multi adapter is not a part of Directx12 itself, it is just something that can be done due to the application directly controlling the gpu's in a system.

Nvidia could lock out their cards from working if they pleased. Although it will be far harder to determine if an amd card is being used with a Nvidia card as the application just talks directly to the graphics card.

 

[andybird123]

This blog post by Microsoft massively disagrees with you;
http://blogs.msdn.com/b/directx/arc...rmant-silicon-and-making-it-work-for-you.aspx

 

[Mauller]

Read the final paragraph...

'The fine grained-control over ALL of the hardware in the system offered by DirectX 12 gives game developers the power to use techniques that were simply not possible in DirectX 11. Our Multiadapter demos only scratch the surface of what creative game developers can do now that they have the ability to directly use ALL of the graphics hardware in the system, even if such hardware has different capabilities and is from different manufacturers.'

It agrees with what i said.

Multi adapter is not a feature that just works in directx 12. it is not an api feature per say, it is just a technique that can be used due to the explicit gpu control.


Just looking at the DX12 documents, there is something called multi-adapter, but it talks about how gpu's are referenced in a system. you still have to write in the support and explicit control.

https://msdn.microsoft.com/en-us/library/windows/desktop/dn933253(v=vs.85).aspx#multiple_nodes

 

[andybird123]

I never said it was a feature that "just works", pretty obvious that its a technique based on other commands. That link says the same thing, that those are core DX12 commands which need to be supported by DX12 hardware to be DX12 compliant, if hardware doesn't support those commands (or chooses not to via a software lock) then it can block multi adapter, but its also not DX12 compliant.

Which still means that Nvidia can't CHOOSE not to support it.

 

[Mauller]

Oh yeah, they have to support the calls that allow multi-adapter to work. Since they are core api calls in the directx api in the first place. which is why i said it would be far harder for them to block support.

but they could do some weird driver trickery that performs checks outside of the directx api. considering they have done it in the past with blocking physx. but tbh they did kind of shoot themselves in the foot with that. considering that people were stil buying nvidia cards to use the physx. All they had to do was make a disclaimer that they do not provide support although it worked perfectly fine.

 

[Orangey]

Coming soon: you must buy an NV-certified mobo to use their gfx cards. Containing hypervisor logic DMZing the PCI slots.

 

[~>Dg<~]

If game devs have to spend time and money enabling things they are not going to bother.

It was the game devs that killed Mantle not AMD.

what many don't realize is game devs make the game how they want. other software "features" are often just monetized benefits.

 

[Orangey]

There are a few people who can push their pet techs (Carmack) however 99% of them follow the path of least resistance and swim with the current.

This is going to end up in the bin with megatextures, hydra, physx etc etc.

 

[Gregster]

Coming soon: you must buy an NV-certified mobo to use their gfx cards. Containing hypervisor logic DMZing the PCI slots.

This is the reason that topics go pear shaped and you do this repeatedly in thread after thread. You stir it up and then when people start responding/arguing, you then go off and report the posts! Just stop it and discuss like an adult.

 

[r7slayer]

Hey i like the sound of this multiadaptor! It would be cool to see the unused IGP on intel CPUs get used in gaming! Although i don't know how this would affect CPU overclocks or Frame times (latency). It is quite interesting but i wouldn't imagine a massive boost in FPS with this tech anyways. Still a very interesting development!

 

[Gregster]

Hey i like the sound of this multiadaptor! It would be cool to see the unused IGP on intel CPUs get used in gaming! Although i don't know how this would affect CPU overclocks or Frame times (latency). It is quite interesting but i wouldn't imagine a massive boost in FPS with this tech anyways. Still a very interesting development!

Not sure if it still works but there was a thing called Hydra from Lucid Logics which used the IGPU alongside your GPU. It worked well and frames really improved but the stutter and hitching was terrible and no way could anyone really play games like that. A good concept though and no reason it can't be sorted for smoother gaming.

 

[Mauller]

It should be far better with DX12 overall compared to the hydra method.

It would also be interesting to see if anyone implements sub-scene rendering where different objects are rendered on different gpu's to split the load. Like how lucid hydra was originally going to be implemented.

 

[CAT-THE-FIFTH]

It could be quite interesting for lower end laptops - imagine if AMD dual graphics or an Intel IGP and a Nvidia graphics chip could be used together more smoothly to boost gaming performance?? It would certainly make gaming better on cheaper hardware.