Monday, August 31st 2015
Lack of Async Compute on Maxwell Makes AMD GCN Better Prepared for DirectX 12
It turns out that NVIDIA's "Maxwell" architecture has an Achilles' heel after all, which tilts the scales in favor of competing AMD Graphics CoreNext architecture, in being better prepared for DirectX 12. "Maxwell" lacks support for async compute, one of the three highlight features of Direct3D 12, even as the GeForce driver "exposes" the feature's presence to apps. This came to light when game developer Oxide Games alleged that it was pressured by NVIDIA's marketing department to remove certain features in its "Ashes of the Singularity" DirectX 12 benchmark.
Async Compute is a standardized API-level feature added to Direct3D by Microsoft, which allows an app to better exploit the number-crunching resources of a GPU, by breaking down its graphics rendering tasks. Since NVIDIA driver tells apps that "Maxwell" GPUs supports it, Oxide Games simply created its benchmark with async compute support, but when it attempted to use it on Maxwell, it was an "unmitigated disaster." During to course of its developer correspondence with NVIDIA to try and fix this issue, it learned that "Maxwell" doesn't really support async compute at the bare-metal level, and that NVIDIA driver bluffs its support to apps. NVIDIA instead started pressuring Oxide to remove parts of its code that use async compute altogether, it alleges.
"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. The only other thing that is different between them is that NVIDIA does fall into Tier 2 class binding hardware instead of Tier 3 like AMD which requires a little bit more CPU overhead in D3D12, but I don't think it ended up being very significant. This isn't a vendor specific path, as it's responding to capabilities the driver reports," writes Oxide, in a statement disputing NVIDIA's "misinformation" about the "Ashes of Singularity" benchmark in its press communications (presumably to VGA reviewers).
Given its growing market-share, NVIDIA could use similar tactics to keep game developers away from industry-standard API features that it doesn't support, and which rival AMD does. NVIDIA drivers tell Windows that its GPUs support DirectX 12 feature-level 12_1. We wonder how much of that support is faked at the driver-level, like async compute. The company is already drawing flack for using borderline anti-competitive practices with GameWorks, which effectively creates a walled garden of visual effects that only users of NVIDIA hardware can experience for the same $59 everyone spends on a particular game.
Sources:
DSOGaming, WCCFTech
Async Compute is a standardized API-level feature added to Direct3D by Microsoft, which allows an app to better exploit the number-crunching resources of a GPU, by breaking down its graphics rendering tasks. Since NVIDIA driver tells apps that "Maxwell" GPUs supports it, Oxide Games simply created its benchmark with async compute support, but when it attempted to use it on Maxwell, it was an "unmitigated disaster." During to course of its developer correspondence with NVIDIA to try and fix this issue, it learned that "Maxwell" doesn't really support async compute at the bare-metal level, and that NVIDIA driver bluffs its support to apps. NVIDIA instead started pressuring Oxide to remove parts of its code that use async compute altogether, it alleges.
Given its growing market-share, NVIDIA could use similar tactics to keep game developers away from industry-standard API features that it doesn't support, and which rival AMD does. NVIDIA drivers tell Windows that its GPUs support DirectX 12 feature-level 12_1. We wonder how much of that support is faked at the driver-level, like async compute. The company is already drawing flack for using borderline anti-competitive practices with GameWorks, which effectively creates a walled garden of visual effects that only users of NVIDIA hardware can experience for the same $59 everyone spends on a particular game.
196 Comments on Lack of Async Compute on Maxwell Makes AMD GCN Better Prepared for DirectX 12
Seriously, how would I have known that ? When this is the first time I hear someone speaking like that ?
Remember how I said:Well, that all still stands and is only even more relevant now.
I am not in a hole, and I don't understand what exactly you are speaking about and how in hell you know what that person meant?
Are you threatening me or what?
My reading skills are ok. I am reading.
What I want to kindly ask you is to leave me alone without all the time analysing in a very negative way my posts and instead trying to respect my opinion.
What AMD does, NVidia doesn't. Also, vice versa.
Now, about that rumour that you could use NVidia and AMD GPUs together in the same system... would that somehow overcome these "issues"?
Image quality? You need to prove that Sony...
You have your head shoved so far up AMD's ass you are crapping AMD BS human caterpillar style (THAT was the first mean thing I have said) and you don't even know it. Since TPU doesn't seem to want to perma ban this clown, I'm just going to put him on ignore. Have fun with this guy people. I can't take the nonsense anymore and risk getting in trouble myself.
www.reddit.com/r/nvidia/comments/3j5e9b/analysis_async_compute_is_it_true_nvidia_cant_do/
EDIT:
Removed the info, read it yourself...
Intel Xeon 18 CPU core per socket running DirectX12 reference driver is the full DirectX12 renderer. ;)
I'm curious if Intel's iGPU takes a performance penalty when using async compute too.
Why do you stress her under FurMark ?
Maxwell is faster than GCN up to 32 queues, and it evens out with GCN to 128 queues, where GCN has same speed up to 128 queues.
It's also shown that with async shaders it's extremely important how they are compiled for each architecture.
Good find @RejZoR
The question is how does this translate to the real world? How many async commands is your average game going to use? 31 or less? 1000s?
All in all I'd say 32 is more than enough for gaming ... there might be benefit of more in pure computePoint is good and all but let's not forget how we are here (mostly) very well used to difference between marketing badges on colorful boxes and spotty support for a new API. Major game engine developers will find a well supported feature subset on both architectures and use them ... hopefully every major engine will have optimized code paths for each architecture and automatic fallback to DX11. Let's try keeping out fingers crossed for a couple of years.
In august adoption of win10 with dx12 gpu owners went from 0% to 16.32% ... hmm ... using full blown dx12 features - maybe in a year
the main goal of having async compute units is not the major parallelization of workload, but having the gpu compute said workload while still performing rendering tasks, which nvidia hardware can't do (all the news floating around seeems to indicate so, also the company hasnt addressed the issue in any way so that pretty much admitting fault).
leave that reddit guy with its c source file with cuda preprocessor tags alone, its going nowhere
We just don't know yet.