DirectX 12: The future of it within the console gaming space (specifically the XB1)

Discussion in 'Console Technology' started by Shortbread, Mar 7, 2014.

  1. Shifty Geezer

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    This thread is for discussing the impact of DX12 on consoles. Speculations on future console hardware bleongs elsewhere.
     
  2. Cyan

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    #1662 Cyan, Jan 10, 2016
    Last edited: Jan 10, 2016
  3. function

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    Seems reasonable. We've known since day one that the X1 has a faster CPU, and since early last year that with the reserves on the six "gaming" cores released that there's more available to games.

    Unfortunately for X1, the most common bottleneck is always going to be the GPU.
     
  4. powdercore

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    Shouldn't the bottleneck be the bandwidth feeding into the GPU and not so much the GPU itself? To achieve 1080p, they must use eSRAM properly otherwise the whole thing falls apart. The problem is that it's difficult to use, but the new eSRAM API in DX12 is supposed to make it easier and more automatic. I recall MS stated there're four stages of adoption of the eSRAM. The last stage was to asynchronously use the Move Engines to move data into/out of memory so that the GPU has has maximal bandwidth without contention with the CPU. I have no idea if this fourth stage has been adopted especially by third-parties. It makes me wonder why MS chose to upgrade the CPU-GPU bandwidth to 30 GB/s while the PS4 CPU-GPU bandwidth is limited to 10 GB/s. What is the bottleneck from the GPU?
     
  5. Arwin

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    Also do we know the impact of the PS4's seventh core becoming (mostly?) available to devs in that context?
     
  6. Metal_Spirit

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    Well... lets see the maximum theorethical CPU diference (pure raw power only).

    According to VGLeaks, Xbox One has a 112 Gflops CPU, and PS4 a 102,4 Gflops.
    My calculations show the exact same numbers:

    Xbox One - 1750Mhzx8coresx8ipc=112 Gflops
    PS4 - 1600Mhzx8coresx8ipc=102,4 Gflops

    When using 6 cores for games we had (Launch)

    Xbox One - 1750x6x8=84 Gflops
    PS4 - 1600x6x8=76.8 Gflops

    A 7.2 Gflops diference (9.3% diference)

    With 50% of the Xbox One 7th Core we have (Xbox 7th Core minimum usage)

    Xbox One - 1750x6.5x8=91 Gflops
    PS4 - 1600x6x8=76.8 Gflops

    A 14.2 Gflops diference (18.5% diference)

    With 80% of the Xbox 7th Core we have (Xbox 7th Core maximum usage)

    Xbox One - 1750x6.8x8=95.2 Gflops
    PS4 - 1600x6x8=76.8 Gflops

    A 18.4 Gflops diference (almost 24% diference)

    With 80% of the Xbox 7th Core and 100% of the PS4 7th Core (Current status with PS4 7th core reportedly unlocked at 100%)

    Xbox One - 1750x6.8x8=95.2 Gflops
    PS4 - 1600x7x8=89.6 Gflops

    A 5.6 Gflops diference (6.3% diference)

    Regardless of the value, its clear Xbox has a CPU advantage.... And granted, 18.4 Gflops is wothy of consideration on CPU bottlenecked games with no assync compute, but on a system with a 530 Gflops diference on the GPU (40.5% diference) , and with GPGPU assync compute capabilities at use, are 5.2 Gflops on the CPU capable of making a real diference?
    And even more if we consider the statements that claim the PS4 API goes deeper to the metal than DX 12?
     
  7. chris1515

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    Maximum difference if CPU is the bottleneck is 1 to 3 frames par second at 30 fps or 3 to 6 frames per second at 60 fps. We don't know if compute is often used in many for physics and AI. The only example I have is Naughty Dog using it for Physics and AI(raycasting for visibility ? ) or Ubi soft soft cloth physics, Guerrilla... But with so many studios using Havok I think part of physics running on GPU is pretty common.


    https://mobile.twitter.com/jqgregory/status/663196554883297280

    From lead programmer Jason Gregory some part of AI and physics(Havok) run on the GPU for Uncharted 4

    For GPU it depends if the title is fillrate bound, bandwith bound or ALU bound... If the title is bandwidth bound ESRAM can help the Xbox One...

    After it depends how you do your particles, in some Digitalfoundry face off the Xbox One lost against PS4 under heavy alpha effect (fillrate?). But when developers will start to use compute particle rendering without overdraw and without using ROPS maybe it will change...
     
  8. function

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    The bottleneck will move around many many times during the course of a frame - perhaps BW one moment, ALU another, ROPs another still. BW and optimal esram use does seem to be a factor going by the various leaks and dev comments, but the single largest "bottleneck" (if you can call it that) seems to be the number of CUs. Of course, if there were more CUs then BW would be more of a factor ...

    Edit: The presentations on DX12 indicate that there are lots of little 'bubbles' that are present during rendering where CUs are stuck waiting for work. DX12 should allow the CUs to keep busy more of the time. X1 is already supposed to have had a lot of work done to allow the CPU to keep the GPU busy though.

    Not necessarily. DX12 is to allows more to be done in parallel, so where one core was once a bottleneck many cores can now create work and submit it to the GPU. So you could possibly be looking at many tens or hundreds of percent increase in performance if this was an enormous bottleneck.

    Of course, in console games this probably won't be as they'll have been designed around the hardware so shouldn't find themselves in this situation.
     
  9. chris1515

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    Because you believe the GNM don't do the same thing... From what I understand the ICE Team is responsible of PS4 API and are competent.

    And I think soon the most advanced rendering engine will not use many drawcall on CPU side but let the GPU auto feeding like in the future Red Lynx title. Going probably from 10 thousands of draw call to hundreds thousands of draw call...
     
    #1669 chris1515, Jan 10, 2016
    Last edited: Jan 10, 2016
  10. chris1515

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    Drawcall was not a problem on console before this generation and is not with a good API....

    For long time PS3 and 360 were capable to do much more drawcall than PC particularly under DirectX 9...
     
  11. iroboto

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    Draw calls can always be optimized, I believe we touched on it much earlier on this thread, a sub topic of "what value do huge draw calls bring".

    Ultimately it appears that if for whatever reason you are on a tight budget than it will help. The only other advantage will come from async compute, being able to submit all your draw calls and async compute calls faster and letting the GPU sort it out seems like a more ideal case than waiting on the CPU to provide work. IIRC whenever the command buffer is empty a specific number of commands must fill the pipeline before the Gpu gets started again, so I guess whatever helps in smoothing out the curve is ideal.

    I just don't think it will apply across the board.
     
  12. function

    function None functional
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    Well according to the guy in the article above (http://gamingbolt.com/the-park-dev-...p-between-ps4-and-x1-cpus#VpChyHoKdG5Q3lO5.99) no, it doesn't.

    Which doesn't mean it can't change. It has nothing to do with whether ICE Team are competent or not, and there's no need to try and reframe this discussion in those terms.
     
    bunge and iroboto like this.
  13. iroboto

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    I think I'm fairly positive that dx12 and GNM are not the same feature set. Nor will they need to be.

    There will come a time in which to increase graphical complexity will require a substantial increase in draw calls that the new APIs provide, but it may not be this generation of consoles. The weight of dx11 games are already crushing them.
     
  14. chris1515

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    From what I understand they did a little game maybe they work with GNMX (DX11 API style for PS4)

    http://www.eurogamer.net/articles/d...its-really-like-to-make-a-multi-platform-game


    Drawcall was a problem on Xbox One but after they improved the API to do DX12/GNM thing like 4A games did two years ago...
     
    #1674 chris1515, Jan 10, 2016
    Last edited: Jan 10, 2016
  15. chris1515

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    The weight of DX11 games... DX11 is just an API and the CPU and GPU in PS4 and Xbox One can do much better GNMX and DX11 are inefficient and can't show what the hardware are truly capable of...

    I think GNMX is an error on Sony side, some dev like the Ubi soft team creating the Crew probably used it for AAA games...
     
    #1675 chris1515, Jan 10, 2016
    Last edited: Jan 10, 2016
  16. iroboto

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    And a hardware and software feature set

    High level APIs are needed as well as low level APIs. The point of an API is to make the lives of developers easier to develop games, with no APIs they would spend an eternity trying to make games

    it's not an error for a company to produce a game.
     
  17. chris1515

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    GNM is an API too and on PS3/360 there were no inefficient Direct X style of API on consoles and games were made.

    At least with Direct X12 use GNM will be a better choice for multiplatform dev... And I hope we will see progress in rendering on PS4 or Xbox One...


    Read more at http://gamingbolt.com/celtoys-inter...e-engine-lead-looks-ahead#2ZUCK3zQ7EYcyhVP.99
     
  18. iroboto

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    fairly certain this is not the whole truth. There are multiple types of dev kits that were available to download.
     
  19. chris1515

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    Old gen no Direct X API style(it was as similar as possible to DX on 360 but with console efficiency...)

    Not like the first version of Xbox One API or GNMX...
     
  20. dobwal

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    Why is that an error on Sony? If you are a PC indie dev who simply wants to port a DX11 like title that doesn't push your typical PC or console, whats the point of a low level api?

    GNMX and the higher level api on the XB1 are there to serve devs whose games aren't cutting edge tech where a lower level api only represents additional headaches and costs.
     
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