AMD Vega 10, Vega 11, Vega 12 and Vega 20 Rumors and Discussion

Discussion in 'Architecture and Products' started by ToTTenTranz, Sep 20, 2016.

  1. BRiT

    BRiT (╯°□°)╯
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    That's SSAA - Super Sampling.
     
  2. Rasterizer

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    As far as I understand the introduction to MSAA that I read, SSAA involves doing the complete render at a higher resolution than the intended display resolution, not just the rasterization stage, as in MSAA. Here's the relevant passage I was basing my understanding on:
    .
    Is this not correct?
     
  3. BRiT

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    You said "rasterizing at a higher resolution" which is SSAA.
     
  4. ToTTenTranz

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    MSAA is a game setting. It's pretty straightforward as the antialiasing setting lights up as e. g. "MSAA 2x".
     
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  5. Ethatron

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    MSAA still only produces 1 shaded sample (pixel shader), the 1 sample is then masked at a higher resolution (coverage), it really is only about contribution.

    Seems not to work then.
     
  6. 3dcgi

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    As Ethatron said with MSAA depth is rendered at a higher sample rate than the pixel rate. Sample rate is different than the final screen resolution. If anything a higher sample rate makes primitive rate be less of a factor.
     
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  7. Anarchist4000

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    MSAA would be limited to edges and transparency (chain link fence, vegetation) in practice while SSAA does the entire scene, essentially downsampling the entire frame. The latter obviously entails far more shading work.

    The coverage and samples would be evaluated within a CU(s) per triangle/workgroup and not significantly affect triangle rate. With three vertices it's just a matter of interpolation to establish coverage.
     
  8. fellix

    fellix Hey, You!
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    Just an advice -- screenshots are best evaluated in PNG format, there's too much compression artifacts in yours. But nonetheless, the MSAA does some work here, but certainly not worth the performance hit.

    Vega just got R600-ed and good thing MSAA is less of importance now than ten years ago. UHD displays and a decent post-process AA (SMAA) is good-enough for the masses.
    Supersampling for the rest.
     
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  9. Alessio1989

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    Does AMD driver support MSAA for DirectX 12 games from control panel? Direct3D 12 does not support MSAA swap-chain like previous version, which made driver MSAA settings more difficult to properly implement, especially with the control of the frame buffers Microsoft give to developers now...
     
  10. ToTTenTranz

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    It's definitely working.
    Its usefulness is just not there, though. As I wrote before, I tweaked the IQ settings as much as possible to bring the jaggies out. With TAA + bloom + DoF these practically go away.



    I know, but at this resolution the original PNG screenshots are 11MB big, which I wasn't able to upload to imgur nor B3D. I can't see much of a difference in detail between the screenshots between the PNG and JPG versions, though.
    Regardless, here's the left half of the screenshot that I could upload to imgur:

    No AA
    [​IMG]


    MSSA 8x
    [​IMG]


    According to some (at least Valve), MSAA is pretty important for VR.
    I don't know if this problem is permanent or it'll be solved in a driver update, but considering all the stuff that's still not working with Vega I think it's the latter.
    There's a multitude of features that are more important to enable before fixing MSAA though, so I don't think this is on their priority list.
     
    #4010 ToTTenTranz, Sep 2, 2017
    Last edited: Sep 2, 2017
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  11. DavidGraham

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    It's still somehow relevant to this day. Many DX12 titles -for example- have MSAA support: Forza 6, Forza Horizon 3, Civilization 6, Warhammer, Ashes Of Singularity, Deus Ex Mankind Divided and the upcoming Forza 7 as well. In addition to many DX11 titles.
     
  12. Alexko

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    I see just as much aliasing on both pictures; doesn't seem to be working at all.
     
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  13. giannhs

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    i think its better to wait and see the october driver and then we can all bash or not amd i havent seen a gcn card that could cope with high levels of msaa in general so nothing really have changed so far
     
  14. Jawed

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    There is MSAA (or something that looks like MSAA). The woman with the lightly coloured legs has strong aliasing on the edges of her legs in the top screenie and much less in the second screenie.

    The large scale jaggies seen on the bright parts of the giant letters where they meet the dark parts of the scene are almost certainly a bug in the way that the game renders "HDR" and performs tonemapping.

    Tonemapping and anti-aliasing disagree with each other. It's only correct to tonemap first then perform the anti-alias resolve and to do all these operations in linear space, not gamma space.

    A good approximation can be determined:

    http://theagentd.blogspot.co.uk/2013/01/hdr-inverse-tone-mapping-msaa-resolve.html

    See the end, which links back to a very old discussion here on B3D.
     
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  15. Rasterizer

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    Forgive my confusion, but I'm still very much a beginner at understanding this stuff. Is the rate at which a GPU performs coverage and occlusion tests not limited by its rasterization rate then? What is the limiting factor in the rate at which these tests can be performed by a GPU then?
     
  16. Infinisearch

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    I'm not sure, IIRC rasterization works on tiles. I'm remembering 64x64 tiles, don't remember from where (might be IHV dependent). If a triangle is bigger than 64x64 it takes multiple clocks to rasterize. What I don't know is if it's 64x64 samples or pixels. Meaning if its 64x64 samples then if lets say 4x msaa is enabled then its effective size is 16x16. If its 64x64 pixels there is no loss in tile size. Maybe someone with more knowledge than me can shed some light on this.

    edit - maybe it was 8x8, my memory is playing tricks on me.
     
    #4016 Infinisearch, Sep 2, 2017
    Last edited: Sep 2, 2017
  17. ToTTenTranz

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    There's a sharpening filter option in the game. Since it's a post effect it could be introducing noise (that's mistaken by aliasing?) to a properly antialiased scene. Maybe that's part of the cause?
    I could disable it and check again how it looks.
     
  18. 3dcgi

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    I don't know as I haven't played with MSAA in a while. I knew forcing in the driver could be less efficient though, hence the question.

    The rate at which a GPU performs coverage (depth) testing is limited by its rasterization rate though GPUs have different rates for depth than color. Depth rates are typically 2x or 4x faster than color.

    Let's consider Vega10. It has a color rasterization rate of 64 pixels/clock with each shader engine being 16 pixels/clock. Any time a triangle covers > 16 pixels it will take 2 cycles to process in one of the rasterizers or it will be split across rasterizers. Any time either of these happens peak geometry rate is no longer achieved. This situation happens quite often, more so at higher resolutions.

    As Infinisearch said the screen is split into tiles with each rasterizer owning some pattern of tiles. This determines if a triangle is sent to multiple rasterizers. Even a 2 pixel triangle can be sent to 2 rasterizers if those 2 pixels happen to cross a tile boundary. It doesn't need to be a large tile. You also can't assume that an IHV always uses the same tile size as this could change based on the chip config.
     
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  19. Rootax

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    Do we know if there are differences between rx drivers and vega fe drivers (gaming mode) at the moment (since they're at the same version 17.8.2 right now) ?
     
  20. Jawed

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    If you want to find out about MSAA performance, you might want to try another game. In fact, try lots of games. And various resolutions.

    This rapidly becomes a hell of a lot of effort with little meaningful payback. Especially if a driver fix arrives with no explanation. A mostly thankless task for the tester.

    This is prolly why some journalists decided simply to troll and hope it goes viral on various Vega-related topics: way less effort and it might just result in a meaningful response - and boy look at that advertising revenue. The entitled millennial generation has infected nearly everyone else, it seems.
     
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