Direct3D feature levels discussion

homerdog said:
Apparently NVIDIA didn't enable UAVs at all stages because they don't support enough UAVs to meet the D3D spec (64 I believe). It is likely that devs can go through some sort of NVIDIA proprietary API to access UAVs at all stages (with limitations of course)
Click to expand...
I wouldn't trust the numbers coming from ARB/shader_image_load_store as a definite indication of hardware capabilities, they're probably just some implementation-specific values.

For example, Radeon R9 280/290 cards report 32 combined image uniforms and 32 for each stage (GL_MAX_COMPUTE_IMAGE_UNIFORMS, *VERTEX*, *TESS_CONTROL*, *TESS_EVALUATION*, *GEOMETRY*, *FRAGMENT*), even though GCN is not really limited by any number as we now know.

Maxwell-2 cards (GTX 750 Ti and GTX 980) report the same numbers as Kepler (GT 650M), that is 48 combined and 8 for each stage .


Note that Microsoft didn't formulate it as "UAVs in each stage" - it's rather "UAVs in all stages", so it depends on how they count these views internally.
 
Kaotik said:
There was an image with slightly different details, IIRC it coupled Maxwell gen 1 with something
Click to expand...

Yes, it placed Maxwell-1 (GM1xx) on RB Tier 1 with Fermi, and Kepler/Maxwell-2 on RB Tier 2.

I tried this combination to see if it corresponds with Max McMullen's numbers above
and strangely it works, but only if you assume that some OEM cards (GeForce GT 630/640/730, GTX 860M) were manufactured using Kepler chips only, while in reality there were multiple versions which also used Fermi chips, as indicated on the Wiki list of Nvidia cards.
 
pjbliverpool said:
According the the DX12 feature levels section here (which I assume DmitryKo has updated)

The Wiki above does include Tonga (285) in the FL11_1 section but lists it as GCN 1.1 so I'm unsure of how correct that is.
Click to expand...

Yep, it was me. I didn't really intend to make a detailed feature matrix there. I corrected GCN reference to read "GCN 1.1/1.2".

I have to put information that is confirmed by publicly available slides and PR documents and doesn't require original research. All we can assume for GCN 1.1/1.2 right now is feature level 11_1 with RB tier 2 and Texture2D tier 2. From the leaked 390X slides, AMD doesn't seem to claim Feature level 12_0 support.


Kaotik said:
It's wiki, before the companies confirm it one way or another, don't trust it on this.
Click to expand...
Yes, exactly.
 
Is there a software which would simply output which featurelevel card x supports? kinda like those OpenGL-extension-checkers
 
DmitryKo said:
Yep, it was me. I didn't really intend to make a detailed feature matrix there. I corrected GCN reference to read "GCN 1.1/1.2".

I have to put information that is confirmed by publicly available slides and PR documents and doesn't require original research. All we can assume for GCN 1.1/1.2 right now is feature level 11_1 with RB tier 2 and Texture2D tier 2.
Click to expand...


HardOcp claimed at the time GCN 1.1 had DX 11.2 hardware support

Third is DirectX support. All of the R9 and R7 and Radeon HD 7000 series support DirectX 11.1 and DirectX 11.2 Tier 1 under Windows 8.1. This 11.2 Tier 1 support is added as a driver update. However, only the R7 260X, R9 290 and R9 290X will support DirectX 11.2 Tier 2 under Windows 8.1. The different tier's represent the level of Tiled Resources feature supported under DX 11.2. R7 260X, R9 290 and R9 290X will have the ability to support the entire feature set, both tiers of Tiled Resources under DX 11.2 in Windows 8.1. Remember also, DX 11.2 is only available under Windows 8.1, not Windows 8
Click to expand...

PS4 also claimed to be DirectX 11.2+

DirectX_11.2__PS4-pcgh.jpg


So wouldn't this make these cards feature level 12_0?
 
No, the "+" only means they have some features not exposed by said API. It doesn't mean those features are necessarily those in DX12 FL 12_0
 
I believe that executeIndirect and Multi Engines are available to FL11 GPUs if I recall reading some of those gdc slides properly. While those features are being introduced with DX12, I don't think it's a requirement for FL 12. Though I could be wrong, I believe those are now considered FL 11 features. Most DX11 GPUs should be FL 12_0 right?

IMG0046698.jpg
 
Last edited:
iroboto said:
I believe that executeIndirect and Multi Engines are available to FL11 GPUs if I recall reading some of those gdc slides properly. While those features are being introduced with DX12, I don't think it's a requirement for FL 12. Though I could be wrong, I believe those are now considered FL 11 features. Most DX11 GPUs should be FL 12_0 right?
Click to expand...
I think the current assumption is that only GCN's might qualify for FL 12 due UAV requirements?

edit:
And Fermi/Kepler/Maxwell gen 1 should be 11_0 even with DX12, since they can't do 11_1 in DX11(.1/2) either
 
Last edited:
pjbliverpool said:
The HardOCP link above claims GCN1.0 parts are only Tiled Resource Tier 1 capable which means they don't qualify for FL 12 or FL 11_2.
Click to expand...
This would make sense, GCN 1.1 was the first GCN device to have Tier 2 Tiled resources.

Do the updated Pitcairn based GPUs have tiled resources tier 2? I was never sure of this. Right now all I know is that Bonaire, Tonga, Hawaii, Fiji have it.
 
pjbliverpool said:
The HardOCP link above claims GCN1.0 parts are only Tiled Resource Tier 1 capable which means they don't qualify for FL 12 or FL 11_2.
Click to expand...
True, should have omitted GCN 1.0, but 1.1 and 1.2 could qualify for 12_0. There's no 11_2 (DX11.2 didn't introduce new feature level), 12_0 is first one to require specific Tiled Resource tier.
 
Metal_Spirit said:
Actually I was talking about the explicit DirectX 11.2 reference. Not the +.
Click to expand...
11.2 doesn't define feature levels, it merely means the GPU is capable of supporting said API, highest feature level in DX11.x is still 11_1
Even if we assume they're referring to Tiled Resources Tier 2 support with it, it's not the only FL12_0 feature.
Of course it's possible GCN1.1 and newer are FL12_0, but there's no conclusive proof of it yet
 
Kaotik said:
11.2 doesn't define feature levels, it merely means the GPU is capable of supporting said API, highest feature level in DX11.x is still 11_1
Even if we assume they're referring to Tiled Resources Tier 2 support with it, it's not the only FL12_0 feature.
Of course it's possible GCN1.1 and newer are FL12_0, but there's no conclusive proof of it yet
Click to expand...

Correct... But that was not were I was trying to get at.
Let me try to explain:
1 - Sony slide is talking about its hardware, not software.
2 - PS4 does not use DirectX at all.
So, from my understanding, it seems Sony is not only claiming the PS4 API supports DX 11.2 features, but that Sony is also letting us know that the PS4 GPU supports in hardware all DX 11.2 Features.
Since there was no feature level defined above 11_1 at that time, I believe that was a claim for hardware support above that feature level. Like the support for Tiled resouces, a DX 11.2 feature (And we all know PS4 supports in hardware Partially Resident Textures).
Besides, the PS4 custom GPU has more than a passing resemblance with Vulcan Islands (GCN 1.1), sharing, at least, it´s GPGPU 8 ACES.
If we are to believe that cards like the R9-290/290x with DX 11.2 hardware support are candidates for feature level 12_0, I would not exclude the possibility of PS4 also be included (and X1 too, of course).
But off course, at the moment, there are no conclusive data!
 
Metal_Spirit said:
Correct... But that was not were I was trying to get at.
Let me try to explain:
1 - Sony slide is talking about its hardware, not software.
2 - PS4 does not use DirectX at all.
So, from my understanding, it seems Sony is not only claiming the PS4 API supports DX 11.2 features, but that Sony is also letting us know that the PS4 GPU supports in hardware all DX 11.2 Features.
Since there was no feature level defined above 11_1 at that time, I believe that was a claim for hardware support above that feature level. Like the support for Tiled resouces, a DX 11.2 feature (And we all know PS4 supports in hardware Partially Resident Textures).
Besides, the PS4 custom GPU has more than a passing resemblance with Vulcan Islands (GCN 1.1), sharing, at least, it´s GPGPU 8 ACES.
If we are to believe that cards like the R9-290/290x with DX 11.2 hardware support are candidates for feature level 12_0, I would not exclude the possibility of PS4 also be included (and X1 too, of course).
But off course, at the moment, there are no conclusive data!
Click to expand...
GCN 1.1 is Sea Islands, Tonga is the only Volcanic Islands (GCN 1.2) GPU at the moment
But yes, the PS4 APU should be GCN 1.1 level, supporting tiled resources tier 2 and all, if driven in DX enviroment. However the "+" still doesn't really mean anything
 
You must log in or register to reply here.
Back
Top