Could Sony create fixed function pipelines for the PS4 even after release?

Discussion in 'Console Industry' started by onQ, Oct 18, 2013.

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  1. onQ

    onQ
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    I know this sound silly but it seems like it's exactly what Sony is planning to do with the 8 ACE's.


    It's a few things that I have read over the last year or so that's leading me to believe this is what they are doing I'll try to go back & find all the quotes later but for now I have a question.

    If Sony was to config the 64 command queues to make the pipelines emulate real fixed function pipelines could they work just as efficient as real fixed function hardware?
     
  2. 3dilettante

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    A fixed-function pipeline is distinguished by it's being fixed.
    It has a function, and that is the task it performs without being able to be significantly modified.

    In the context of this console, how does one create a pipeline that can--through the act of changing its function--become a pipeline that cannot change its function?
     
  3. patsu

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    I am surprised you didn't lose it, 3dilettante. Great patience.
     
  4. onQ

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    By creating the fixed function pipelines at the driver level once you figure out just what fixed functions you want the pipelines to be used for.
     
  5. patsu

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    In the usual terminology, I believe fixed function = non-programmable. If the ACE and the associated pipeline and CUs are programmable, then they cannot be called fixed functions by definition.

    May want to rephrase your thoughts.
     
  6. 3dilettante

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    There is a physical component inherent to the defining whether something is fixed-function, and it is also this physical component from which it derives its utility.

    A fixed-function pipeline or unit can strip out a lot of logic necessary for problems outside of its target workload.
    The means by which it can be controlled--be it the control logic or ability to receive software commands that could retarget it--can also be fixed or mostly stripped away.

    Software instructions don't create circuits that aren't there. Barring something more exotic, it's a limitation of conventional silicon integration and true for the SoCs described so far.
    If they can, it's something like a programmable gate array. A one-time programmable gate array is almost what you are describing, but it would be a bad idea because it is one-time.
    A FPGA can be reprogrammed, but then as a whole the device is not fixed-function.
     
  7. onQ

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    I said create fixed function pipelines.


    Kinda but what I read about was actually config-able pipelines instead of FPGA to get about the same result. I'll search for it.




    Also this is one of the articles that triggered this thought.

    http://www.gamasutra.com/view/feature/191007/inside_the_playstation_4_with_mark_.php?print=1

     
  8. Brad Grenz

    Brad Grenz Philosopher & Poet
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    Your question doesn't make sense. Sony can create specialized libraries that leverage the hardware in certain ways for game developers to use, just like they did throughout the life of the PS3, but you wouldn't call them "fixed function pipelines" because they'd be software, and developers would be free to modify them for their needs.
     
  9. 3dilettante

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    The more configurable or alterable something is, the less it can be described as fixed.
    If there are specific areas of silicon that you are describing as being able to be configured or programmed to perform different and changing tasks past the point of manufacturing, fixed-function isn't the term for them.
     
  10. Pete

    Pete Moderate Nuisance
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    Efficient in what sense? Transistor count / area / power / manufacturing cost? Or do you mean in terms of giving developers ideal or optimum use cases for the hardware? Isn't that what Cerny & co. did for the PS3 (mostly Cell)? And isn't that the point of flexible hardware, to accommodate better algorithms down the line rather than fixing you to one? Isn't your very question (Sony doesn't know what to bake into the GPU at launch) an argument against fixed functionality? Who's to say Sony doesn't discover even better "fixed functionality" down the road, in which case they've wasted die space if PS4's GPU had a bunch of fixed functionality to begin with?

    Do you mean simplifying development by offering optimal paths to achieving certain effects? Don't devs get there with experience / libraries / APIs / middleware?

    Or are you talking about something like a PhysX or 3D sound "pipeline?" (That'd take me back to xp / libs / APIs / mw, but what do I know.)

    What advantages do you see from fixed function pipes? Efficiency is a nebulous term until you say what it is you want the GPU to be efficient at.
     
  11. onQ

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    I found the PDF that I read a few months ago http://www.retarget.com/resources/pdfs/cox-multicoreexpo10.pdf



    I'm not saying that the hardware would be fixed function I'm saying create what would look like a fixed function pipeline so that the software would see it as if it was running on fixed function hardware.



    OK this is what I'm saying create fixed function pipelines so it would be like this 'Pipeline 1 will run the physics code & Pipeline 2 will run the lighting code' because the pipelines are designed to look as if they are actually hardware created for Physics & Lighting.


    The fixed function pipelines haven't been created yet but in a few years the devs & Sony will chose how the data paths should be laid out to create the fixed function pipelines.
     
    #11 onQ, Oct 18, 2013
    Last edited by a moderator: Oct 18, 2013
  12. 3dilettante

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    It sounds like you're asking if they can create a software service that performs certain functions, and then put it behind an interface that presents a certain set of inputs and outputs to the programmer trying to use the service.

    The answer to that would be yes, but that wouldn't be unique. Abstracting away nitty-gritty details would come with middleware or modularization done by the engine programmers.
    On the other side, fixed-function hardware can have more software or hardware added to massage away some of the rough edges so that software can more readily use it.

    The interface wouldn't normally create the impression that there's a specific fixed-function hardware pipeline behind it unless it's actually there for the sake of emulation.
    Having ultra-specific timings, working around bugs, and juggling random control registers doesn't produce any benefit unless you had games like those on ancient consoles that specifically took advantage of things like cycle timings and scan line progression for different effects.
     
  13. Grall

    Grall Invisible Member
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    What you're saying doesn't make sense, it is not possible, and even if it was, there'd be no benefit to it as even if you could dedicate certain compute queues to certain tasks it would not speed anything up in any way.

    Well, it isn't. All the pipes are functionally identical, from what we know (and from what logic would dictate.)

    Reality just changes to fit whatever ideas you come up with, is that what you're essentially saying here...? ;)

    NO. Doesn't work like that!
     
  14. Laa-Yosh

    Laa-Yosh I can has custom title?
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    What is this I don't even
     
  15. BoardBonobo

    BoardBonobo My hat is white!
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    If the entire SoC is based on an fPGA then it could potentially be reconfigured to be fixed function or whatever.

    As it is, it's just not going to happen.
     
  16. onQ

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    It didn't make sense to any of you when I posted about the PS4's GPU being able to run Graphics & Compute together neither.
     
  17. Grall

    Grall Invisible Member
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    What, you mean the ability which sony explicitly said was there, and which we knew it had all along?

    I don't get it. You didn't reveal anything new then, and you're making something up out of nothing now. What's the deal here, you seeking attention and approval, or what? :)
     
  18. patsu

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    Correction. Some of the folks here do know way before you posted your question. But they were not sure if you knew exactly what you typed.
     
  19. onQ

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    I'm not seeking attention or approval.



    Some people was flat out saying that it couldn't be done & trying to make it seem as if I was saying that the GPU had 2X as much power or something.



    Anyway I'll explain again.



    Instead of creating 3 or 4 fixed function hardware chips you will use one general purpose chip but creating 3 or 4 fixed function pipelines.
     
  20. Shifty Geezer

    Shifty Geezer uber-Troll!
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    :evil: No-one ever said concurrent GPU + compute was impossible. Everyone said you could not have compute in addition to 1.84 TF of GPU work which is what you said. Let me quote...

    If you never meant 1.84 TF of graphics and extra compute on top of that, you failed to express yourself clearly. Similarly, here you talk of fixed-function pipelines in flexible hardware, which is an odd concept and one everyone's getting muddled with fixed-function hardware. You do have a habit of asking questions or presenting ideas in a way that conflicts with the general board's interpretations and leads to rather flustered discussions.

    Why would you? You have a thread on this board that you started where you were asking if PS4 would result in better software renderers, precisely because of flexibility. There's no reason in walling off parts of the hardware to enforce use except in the case of doing so at the hardware level where the restricted flexibility is balanced out with greater relative performance. 'Fixed-function pipelines' can be implemented at the middleware level, providing developers with hooks to do the basic chores of rendering, but the hardware remains open to be exploited however the developers choose. It's the only sensible way to do it. One could, in theory, provide a forced software interface for various functions that can then be implemented in dedicated hardware in future machines, but that'd be a crazy step backwards, like implementing GC's fixed functions in shaders and then replacing your shader based GPU with a fixed-function one.
     
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