Xbox One (Durango) Technical hardware investigation

Discussion in 'Console Technology' started by Love_In_Rio, Jan 21, 2013.

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  1. anexanhume

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    There's been some confusion going around. eSRAM is essentially eDRAM. Both have 1 transistor and 1 capacitor per cell. I'm sure someone else can explain more details.

    edit: This is decent.

    Because if it's on an APU, that's more budget for the GPU. Jaguar is still well suited to this task. Low power, OoO with AVX and other advanced FP capabilities. The only thing I'd rather have is a mobile quad core Haswell, which isn't possible as an APU solution with an AMD or Nvidia GPU.
     
    #1001 anexanhume, Feb 12, 2013
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  2. french toast

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    Mmm ok...but the gpu isnt massive. .and that doesn't explain the puny clocks...
     
  3. AlphaWolf

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    There's different forms of eSRAM, what you're describing is 1T-SRAM which is really eDRAM. True SRAM has 6 transistors per bit (or more). We're all just guessing at what is actually in durango.
     
  4. anexanhume

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    No, it's not. With the extra custom circuitry plus the GPU, they probably hit a less aggressive overall TDP compared to generations past.

    The puny clocks are because that's what Jaguar was designed to. It won't work at significantly higher clocks because the logic wasn't designed to close timing at those numbers. They would have had to design a whole new CPU.

    Which AFAIK is never referred to as eSRAM, because it only comes embedded. And we'd never see SRAM this size on this process.
     
  5. AlphaWolf

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    1T-SRAM isn't usually referred to as eSRAM either, which is why we're still guessing.
     
  6. anexanhume

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    Perhaps it was chosen deliberately to demonstrate that it wouldn't have the same trappings as the xbox 360 eDRAM but plain 1T-SRAM sounds too much like "cache"?
     
  7. sir doris

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    Well they remained everything else ;)
     
  8. MrFox

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    I'm still thinking it's plain SRAM. But the 100GB/s is puzzling, is it possible the eSRAM is on a daughter die like the 360? That would open up some additional possibilities for pseudo SRAM, because many of them require a special process.
     
  9. patsu

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    Well, gamers may still not see the benefits of these display planes until they see the final OS. Even if display planes were used as part of the display engine in car kits, older consoles and PCs, people are generally unaware of them. In games, the multiplatform developers will not let the presence/absence of display planes compromise parity. They have other (software-based) optimization techniques.

    In traditional console games, we don't typically have other apps running in parallel until in-game blade UI and XMB shows up. When MS starts to flaunt these free composition and alternate display in their apps and OS UI, like iOS transitions, the display planes should standout more.
     
  10. inefficient

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    High clock speeds are generally only attainable by having very long pipelines with very short stages. Essentially you can get your clock rate up by doing less work per cycle.

    A more sophisticated cpu with a lower clock but a more efficent pipline can achive much greater real world throughput just by doing more work per cycle
     
  11. anexanhume

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    If they only needed 100GB/s, regular SRAM would be extreme overkill. A daughter die would also go against the idea of a monolithic APU. I think their goal is one die, simple process, no more complexity than is needed.
     
  12. MrFox

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    But any memory other than standard SRAM does add complexity, and most require special process steps, are not necessarily available on 28nm yet, and cause trouble with later shrinks. Maybe SRAM gives them much better latency, and that could be more useful for GPU compute tasks than bandwidth.
     
  13. anexanhume

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    SRAM is unlikely simply because it would be gigantic.
     
  14. french toast

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    Cheers..well that explains that then...
     
  15. french toast

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    Cheers just had a read...1TSram is 1 transistor dense stuff. .where as the real sram is called 6Tsram and is much larger.
     
  16. astrograd

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    The OS plane will be used for that. The other two probably won't.

    This comment seems misleading since we know why devs utilize things like dynamic and/or adjusted res. It's usually in a game that needs every ounce of graphics power squeezed out of it in the first place. The display planes are there to help give devs more control over resource management. And if you read the background/summary of the patent it is pretty clear their goal is absolutely to offer QoS guarantees based on saving resources. I would also disagree with your suggestion that dynamic res/fps/etc isn't to be considered a component of optimization.

    I know that, but my initial post on that was misleading as it was drawing an inference from that specific image which upon further reading was clearly incorrectly based on my misunderstanding of it. The wheel was part of the game plane.

    I am more curious to see how far devs can stretch the HUD plane in terms of rendering non-HUD stuff to it. Lots of modern HUDs these days are no longer just straight up 2D overlays, so presumably there is leeway there. If there is a way to have some meaningful elements of the game world being displayed in that HUD plane (arm/gun in an fps or car interior in a racing game, etc) that could be a pretty huge deal imho. I'd imagine others here could outline some of the limitations (or their guesses of the limitations) based on how the planes are being blended?

    If there is no real technical distinction being made in the 2 application/game planes other than forcing one to be on top of the other, than maybe devs could leverage it as a foreground/background sort of thing? If so, that could seemingly add a LOT to the resource saving side of things I'd imagine since depending on the cutoff having lower res backgrounds isn't really a problem. Hell, devs use system resources as it is just to blur out backgrounds anyhow! :smile:

    But it costs resources to do it via software...moreso than it would on Durango's setup, no?

    I am also interested in seeing this. I know very little about virtual memory but it sounds like it could be the sort of things that might save Durgano's setup a lot of processing and bandwidth to get the same output. If that is true it would make a lot of Durango's design decisions actually make sense.
     
  17. astrograd

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    It may be possible that their design decisions are based on delivering a box built to leverage virtual memory/textures/geometry and heavy tiling. Based on what I've read such an approach would be able to net you the same visual output with significantly less powerful specs. I think they probably wanted to spread out the processing and bump up efficiency across the board specifically for this reason. Taking high end software concepts and implementing solutions for them via hardware sounds like something devs would be thrilled with.
     
  18. patsu

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    The DME is an inherent part of the system. It will be used for "everything".

    Where dynamic resolution is concerned, the QoS is guaranteed by sacrificing something, as the patent put it. I didn't say it's not a component of optimization. I pointed out there are other software optimization techniques developers may use to avoid sacrifices in a standalone game. The developers will/should focus on those techniques first.

    The display planes are helpful in compositing (for free). But within a game, I doubt the saving is great. They can control the update rate, timing, quality, quantity, and region of different elements by software.

    It seems that the display planes are more useful and their benefits more apparent when you have layers of information from different sources. e.g., Custom software HUD over a dedicated video decoder output, OS mouse cursor over an app window, miniaturized game output in OS screen, AR over Kinect video or Blu-ray. It may mean Durango can compose all the different output together while ensuring the responsiveness of the OS. These are part of the "new" experiences I expect in the Durango OS.

    Yes, but how resource intensive is the final compositing for a game ? The GPU is very efficient at pixel operations, especially when all the in-game visual elements are generated by it. The programmer has full control over what not to draw, and how frequently to draw the visible ones.

    As others have pointed out, without the display planes, it is not uncommon to have color conversion, scaling, compositing done as part of the display engine too (Many have simple hardware overlays to do this). The Durango display planes seem more elaborate in that you can divide them into 4 quadrants to mask obscured output. As such, they may be there because Durango's OS relies on them for a new and consistent experience.
     
  19. Silent_Buddha

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    PS2 also had a small army of processors and did quite well compared to relatively more straightforward Dreamcast. That one turned out differently. :)

    Regards,
    SB
     
  20. Silent_Buddha

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    That last little bit also made me think that it could give a graphical advantage in some respects if some game, for example, only ran at 720p or any other sub 1080p resolution, but Durango's Game UI was at 1080p while Orbis's Game UI was at the same resolution as the game.

    For some side by side comparison like Digital Foundry, you'd be able to pick it apart. For your average consumer though they may think the game with the sharp native res UI is actually better looking than the other one, even if the other one had, say, better shadows and lighting.

    Of course, if that were the case, that would force Orbis developers to also have a native res UI. But if there's no hardware support it may require more GPU resources, thus leveling the playing field regardless.

    Regards,
    SB
     
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