DX12 Multiadapter Feature

[Dave2150]

http://blogs.msdn.com/b/directx/archive/2015/05/01/directx-12-multiadapter-lighting-up-dormant-silicon-and-making-it-work-for-you.aspx

Are you one of the millions of PC users with a laptop or a desktop system with an integrated GPU as well as a discrete GPU? Before Windows 10 and DirectX 12, all the performance potential from the second GPU goes unused. With DirectX 12 and Windows 10, application developers can use every GPU on the system simultaneously!

Are you an elite power gamer with multiple graphics cards? Well, by giving the applications direct control over all of the hardware on the system, applications can optimize more effectively for the ultra-high end, squeezing even more performance out of the most powerful systems available today and in the future.

We’re calling this DX12 feature “Multiadapter”, and applications can use it to unlock all that silicon that would otherwise be sitting dormant doing nothing.

At //build 2015 we both announced the Multiadapter feature and showed several examples of how it can be used.

Square

This sounds awesome - all these mainstream Intel CPU's that have an increasing larger amount of the die devoted to 'useless' IGPU now finally has a use for gamers!

I'm quite keen to see how Broadwell for desktop will perform with it's Iris Pro 128MB eDRAM, and how much of an improvement Skylake's IGPU will bring, when coupled with a decent dedicated GPU.

Interesting times ahead

 

[Dave2150]

This is a directx12 feature, built into the API. I'm reserving judgement until we see a thorough review/benchmark of it etc, though as it's from Microsoft and build into DX12.

The mainstream I5's, I7's etc with the large IGPU built in is literally sat there doing nothing. If it can be used automatically by DX12 to improve performance, then it's a win win scenario.

Intel have such a huge market share, I can understand why Microsoft decided to build this into DX12 - a very large % of the market will benefit from it.

 

[Dave2150]

It's worth noting that at this stage, Microsoft only give one example of how the IGPU will be utilized - post processing.

Quoting from the article linked in OP:

Virtually every game out there makes use of postprocessing to make your favorite games visually impressive; but that postprocessing work doesn’t come free. By offloading some of the postprocessing work to a second GPU, the first GPU is freed up to start on the next frame before it would have otherwise been able to improving your overall framerate

The image above shows how this post processing work on the IGPU would work, when coupled with two NVIDIA GPU's in SLI. This shouldn't affect the direct pipeline of the GPU - so we shouldn't see any frame pacing issues or stutering issues with this implementation. It also shows that this feature is being developed with multiple dedicated GPU's in mind, as well as single cards, so it seems a comprehensive solution.

As the article mentions, almost every game utilizes post-processing, so this really should be a big win win for all those who have an IGPU doing nothing.

It should also be noted that Microsoft are no doubt working with NVIDIA to implement this feature, so it goes without saying that NVIDIA's drivers will be top notch and will take advantage of this feature out of the box, when released.

*Conspiracy hat on* - I wonder if Intel pressured Microsoft into adding this feature into DX12 - it will only increase the already massive gap between AMD and Intel CPU's - since the high end FX CPU's from AMD dont have an IGPU at all, including the Zen CPU's due out next year. Hmm, being I'm being paranoid, though it seems quite an ingenious way to further handicap the competition to me