Get your popcorn ready: NV GPUs do not support DX12 Asynchronous Compute/Shaders. Official sources included. (self.pcgaming)
inviato
12 ore fa * da SilverforceGFor the ELI5: https://www.reddit.c...support/cullj3d
This all came about due to Oxide's upcoming DX12 RTS, Ashes of the Singularity. When they released the benchmark, various places found that AMD GPUs had a massive performance gains (partly DX11 driver overhead, partly because GCN's ACEs are doing nothing on DX11), but NV GPUs actually do worse in DX12.
NV fired some pretty fine words at Oxide, dissing their game as not representative of DX12 games, and claiming they had a MSAA bug. Oxide fires back saying the bug is actually in NV's drivers and offered to help them fix it.
They made a nice blog about DX11 vs DX12 where they clarified it and that they were not out to gimp any hardware, but they play fair by the DX12 book.
This escalated on the tech forums, getting heated accusations thrown around, and so Oxide came into the discussion with this bombshell:
Maxwell doesn't support Async Compute, at least not natively. We disabled it at the request of Nvidia, as it was much slower to try to use it then to not.
Followed up with this:
Personally, I think one could just as easily make the claim that we were biased toward Nvidia as the only 'vendor' specific code is for Nvidia where we had to shutdown async compute. By vendor specific, I mean a case where we look at the Vendor ID and make changes to our rendering path. Curiously, their driver reported this feature was functional but attempting to use it was an unmitigated disaster in terms of performance and conformance so we shut it down on their hardware. As far as I know, Maxwell doesn't really have Async Compute so I don't know why their driver was trying to expose that.
I suspect that one thing that is helping AMD on GPU performance is D3D12 exposes Async Compute, which D3D11 did not. Ashes uses a modest amount of it, which gave us a noticeable perf improvement. It was mostly opportunistic where we just took a few compute tasks we were already doing and made them asynchronous, Ashes really isn't a poster-child for advanced GCN features.
Our use of Async Compute, however, pales with comparisons to some of the things which the console guys are starting to do. Most of those haven't made their way to the PC yet, but I've heard of developers getting 30% GPU performance by using Async Compute.
And finally this, they basically challenge NV to prove them wrong.
There is no war of words between us and Nvidia. Nvidia made some incorrect statements, and at this point they will not dispute our position if you ask their PR. That is, they are not disputing anything in our blog. I believe the initial confusion was because Nvidia PR was putting pressure on us to disable certain settings in the benchmark, when we refused, I think they took it a little too personally.
It looks like Oxide is angry at NV since NV tried to make them look like fools despite the problem being with their hardware, so Oxide took it personally and go public.
And now, AMD chimes in! u/AMD_Robert (Robert Hallock):
NVIDIA claims "full support" for DX12, but conveniently ignores that Maxwell is utterly incapable of performing asynchronous compute without heavy reliance on slow context switching.
GCN has supported async shading since its inception, and it did so because we hoped and expected that gaming would lean into these workloads heavily. Mantle, Vulkan and DX12 all do. The consoles do (with gusto). PC games are chock full of compute-driven effects.
Looks like this is escalating, time to prepare the popcorn and see NV's response!
As to why Async Compute/Shaders are so important in DX12 & future cross-platform games:
Compute is used for global illumination, dynamic lighting, shadows, physics, post-processing (including even AA). If it can be offloaded from the main rendering pipeline and done asynchronously in parallel, it can lead to major performance gains. As such, GPUs that support it will see major performance uplift and in theory, GPUs that do not support it, will have no benefit, it reverts back to the normal serial rendering of graphics & compute.
Async Shaders are vital for a good VR experience, as it helps lower latency of head movement to visual/photon output. I posted on this topic awhile ago:
https://www.reddit.c...sue_of_latency/
Because I suspected it may be related to their Async Shader pipeline, now it looks to be confirmed.
For those asking (which many of you have done, I didn't feel like responding over & over) whether they should buy NV GPU or AMD GPU, its ultimately your choice. But for me, I tend to hold my GPUs for a few years (~3), so I do buy with current performance AND "future-proof" in mind.
I still have rigs with R290s in it, and back then, they were cheaper than 780 and competed against it. Nowadays R290 is far in front of the 780. So you could say the R290 was more future-proof than the more expensive option, 780. A similar situation exists for R290X vs the 780Ti (which was quite a lot more expensive).
As for which GPUs I think is more future-proof now, it's definitely AMD GCN GPUs. Why? Because of how closely similar DX12 and Vulkan are. Vulkan, as some of you may be aware, is Mantle (AMD's console-like API) with a new name/logo.
This picture says a thousand words: http://i.imgur.com/q1AcNMg.jpg https://www.khronos....n-GDC_Mar15.pdf
There is zero doubt that AMD GPUs will benefit greatly with DX12. We can't really be certain the same can be said of Kepler/Maxwell. Especially now with Oxide (one of the 2 key studios who led the way to Vulkan/DX12, along with DICE!) & AMD's statement on the matter.
The choice is yours to make.
Versione tldr, tutte le gpu maxwell non supportano a livello hw le dx12. Comprese le 980 e giu di li.
byebye nvidiacuck.
