DirectX Developer Day 2020

Discussion in 'Rendering Technology and APIs' started by Kaotik, Mar 19, 2020.

  1. Kaotik

    Kaotik Drunk Member
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    Microsoft's DirectX Developer Day 2020 is about to begin just about now at https://mixer.com/DirectX

    On agenda:
    - The New features and unprecedented opportunities of DirectX 12 (Jianye Lu)
    - The New Standard for Next Gen Games (NVIDIA)
    - DXR Tier 1.1: Adding functionalities and efficiency (Jianye Lu)
    - DXR Tier 1.1 Running on AMD RDNA 2 Hardware (Dave Oldcorn, AMD)
    - Reinventing the geometry pipeline: Mesh Sahders in DirectX 12 (Shawn Hargreaves)
    - Advanced Mesh Shaders (Martin Fuller)
    - DirectX 12 Sampler Feedback (Claire Andrews)
    - PIX on Windows (Austin Kinross)
    - HLSL Compiler (Michael Doughterty)
     
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  2. DavidGraham

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  3. DegustatoR

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    Everything in DirectX is developed by MS with a lot of input from all GPU h/w vendors.
     
  4. Kaotik

    Kaotik Drunk Member
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    But not alone with MS ;) Of course NVIDIA was involved, just like AMD, Intel, Imagination and probably Qualcomm too.
     
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  5. Scott_Arm

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  6. Alessio1989

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    Ding-dong, Geometry Shader is dead! :-D
     
  7. milk

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    I don't get it
     
  8. BRiT

    BRiT Verified (╯°□°)╯
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    A cultural reference to The Wizard of Oz.
     
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  9. Lurkmass

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    It should be highly advised for console or AMD hardware developers to use the DXR Tier 1.1 inline ray tracing feature to get the most optimal performance out of their GPU. DXR Tier 1.1 maps nicely to the new upcoming AMD graphics architecture and using the inline ray tracing feature will most likely trigger their fast-paths in their hardware. Treat the practices from DXR Tier 1.0 as being effectively 'deprecated'.

    No idea what the 'fast-path' would be on Nvidia hardware or whether it even matters in terms of performance.
     
  10. OlegSH

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    Have you watched the presentation on DXR 1.1 you linked?

    It discusses quite common shading optimisations for all GPUs, thread divirgence is the issue for all GPUs.

    In other words, these are architecture agnostic optimizations.

    The same can be said about new features in DXR 1.1, there is nothing specific for AMD.

    GPU work creation for rays dispatching and software scheduling is a good thing for all GPUs.
     
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  11. Lurkmass

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    Doubt it since this is an IHV representative from AMD doing this presentation.

    Also I doubt divergence is much of an issue on Nvidia hardware since their GPUs have independent thread scheduling which keeps track of the divergence with a program counter per lane.

    DXR Tier 1.1's inline ray tracing feature is likely to be an AMD centric fast-path to doing ray tracing on their hardware. Maybe Intel hardware could potentially work similarly ?

    Whatever it is that Nvidia taught developers with DXR Tier 1.0, it's probably lies and it does not match how ray tracing works on consoles.

    I still don't know what the exact fast-paths or slow-paths are for Nvidia's ray tracing implementation.
     
  12. DavidGraham

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    Some tidbits on the discord channel of the GDC presentation:

    Microsoft themselves reiterated the same sentiment, and stated that both DXR1 and DXR1.1 don't replace each other, they exist together and complement each other.

    https://devblogs.microsoft.com/directx/announcing-directx-12-ultimate/
     
  13. Lurkmass

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    That still doesn't change the fact that this goes against AMD's programming advice for their hardware. DXR Tier 1.1 with inline ray tracing is the most likely way to hit AMD's fast-paths even with complex shaders in the vast majority of the cases.

    As far as AMD are concerned, DXR Tier 1.0 is nearly obsolete crap to them. If a developer is trying to optimize ray tracing on AMD hardware then they should avoid it as much as possible.
     
  14. DavidGraham

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    AMD is trying to encourage developers to use as little shaders as possible in their RT implementation to use the inline DX1.1 features. Most likely because otherwise RT will be slower on AMD hardware. Maybe significantly slower as well. I guess it will depend on the nature of the game and the required achieved look, some games will do fine with minimalistic shader approaches, some simply don't.
     
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  15. pharma

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    I'm sure there will be demos showing performance and visual quality of both Nvidia and AMD implementation using both DX1.0 and DX1.1. So far not impressed with the DX1.1 demo visuals.
     
    #16 pharma, Mar 20, 2020
    Last edited: Mar 20, 2020
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  16. OlegSH

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    Such a childish argument.
    All hw vendors participated in DXR 1.1 development, and yes, AMD presented it, so what? In the same way, nvidia guys presented DX12 many times on different conferences.

    That's a programming model feature that enables execution of mutexes and other sync primitives on a single thread level without causing deadlocks on GPU. It enables new algorithms on GPU and simplifies CPU code porting. This feature enables MIMD like programming model, yet performance wise it still behaves like SIMD. It is not a performance feature, it doesn't help with thread divergence performance problems.

    Certainly it can be a fast-path in comparison with dynamic-shader-based raytracing on AMD hw for whatever reason, but why do you think simplified inline raytracing shading will cause any slowdowns on Turing?
     
  17. Lurkmass

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    Did I somehow state that inline ray tracing was a slow-path on Nvidia hardware or did you and the others start getting defensive ?

    And one should always take caution with vendor because what speak of does not necessarily apply to other hardware vendors.
     
  18. pharma

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    March 19, 2020
    https://venturebeat.com/2020/03/19/microsoft-unveils-directx-12-ultimate-with-improved-ray-tracing/

    March 20, 2020
    https://www.pcworld.com/article/353...ting-graphics-tricks-across-pcs-and-xbox.html
     
    #19 pharma, Mar 20, 2020
    Last edited: Mar 20, 2020
  19. DegustatoR

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    That's funny considering that official MS recommendation is to use 1.0 capabilities (which are a part of 1.1 now btw so saying that 1.0 is "crap" means that 1.1 is also "crap" in like 90% or so) when you're actually doing a lot of RT and use inline trace ray when you're doing just a little of it.
     
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