Velocity Architecture - more than 100GB available for game assets

Discussion in 'Console Technology' started by invictis, Apr 22, 2020.

  1. liams

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    Im pretty sure this is the reason the COD is so massive, irrc its because they couldn't rely on the cpu having enough free processing capacity to decompress textures from a more compact format on the fly
     
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  2. rntongo

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    Exactly! Unless the PS5 has more RAM, the disk I/O subsystem in both systems performs despite the PS5 having twice the throughput. Looking at MK 11 ultimate, which is upgraded for both systems, loading into gameplay takes the same amount of time. Loading into the game from the main menu is faster on the PS5 though but its down to the Series X showing so many screens on start up. So when games get really optimized it will be more like 2 seconds vs 4 second load times or even less. No discernible difference.
     
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  3. thicc_gaf

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    The only monkey wrench that might get thrown into this are ballooning game sizes as the gen goes on, but I think that's actually more a worry for storage space than loading times. Which means prices on PS5-compatible SSDs and expansion card (Series systems) better come down sooner rather than later!

    I'm really interested if games start leveraging upscaling techniques and therefore can go with smaller texture files in their packages. Ninja Theory have talked about work from their end on this so I'm definitely looking forward to Hellblade II on that note (and visual mastery note as well, considering how good the first game still looks going seven years later).
     
  4. BRiT

    BRiT (>• •)>⌐■-■ (⌐■-■)
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    Given the number of gamers who said they see no benefit with Quick Resume, to go between multiple games, they really don't need more than 300 GB of space, since by their own statements they only ever play one game maybe two during the same period.

    For everyone else, using an external SSD as cold-storage for games needing to be on internal NVME to play is a solid experience. The copy speeds between the two are quite fast. You get 2x the space for the same cost (2TB SSD vs 1TB Storage Card).
     
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  5. rntongo

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    Here is a link to a recent Dirt 5 dev interview. The Series X can do 10GB in 2 seconds without the decomp block.With only about 13.5GB RAM for games, It's more than enough for instant load times once they use the decomp block. So it means most games are being held back by game designs based off current gen, otherwise they would be utilizing these speeds.
     
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  6. pjbliverpool

    pjbliverpool B3D Scallywag
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    Yes I saw that and thought what a complete load of BS it was. How can you load 5GB raw data per second from a drive that peaks at 2.4GB/s?

    Heck I think the XSX may even be limited to 2 PCIe 4x lanes which means even if the SSD itself did somehow magically double in speed, the bus with which it communicates to the rest of the system couldn't carry that much data.

    More likely the source is just confused and he's talking about compressed data.
     
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  7. DSoup

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    It's an interesting claim. Until he explains how he tested, i.e. if it was small amounts of repeated reads/writes collectively adding up to 10GB, the cache may make this possible. ¯\_(ツ)_/¯
     
  8. Jay

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    I saw that a dev wrote that, I didn't even consider it worth my time to see what was said.
    Even if it was possibly lost in translation.
     
  9. turkey

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    I do not believe he mentioned compressed or not when he first says this. Then he mentions it again but I think "compressed" in the context of the using the full suite of Velocity architecture, bcpack or other techniques a developer may utilise.

    LX compression I would assume is basically raw as far as a developer sees things. All data will go through that block Regardless, I would think the GDK Lz compresses and encrypts any asset you include.

    The same for PS5 which is why Cerny says devs have nothing to do to take advantage of the hardware. Your only challenge is throwing stuff at it to saturate the system.
     
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  10. rntongo

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    He's a technical lead on a major title with years of experience, so I don't think he misspoke but he wasn't clear how its achieved. I agree he wasn't clear and the interviewers didn't press him to clarify because they lack knowledge about basic computer architecture. It should be clarified how its possible without the decomp block. I'm guessing there is a separate wider bus link between the SoC and the RAM. Because in any case how does the Decomp Block work with the DMA to send large decompressed amounts of data into RAM? The CPU could theoretically do the same right?
     
  11. pjbliverpool

    pjbliverpool B3D Scallywag
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    Here's the exact quote:

    I've highlighted a couple of bits that make me wonder if they were maybe using faster hardware in the early days? The interface is PCIe4 and in the timescales they are talking about the fastest PCIe4 drives were around 5 GB/s on a 4x interface which may have been simple off the shelf models plugged into PC's that were spec'd similarly to the final XSX hardware. So if he was testing Direct Storage on early hardware it's conceivable that he was seeing 5GB/s throughput in those early tests.

    I can't see how it's possible on the current final hardware though. We know the interface is 2 lanes of PCIe 4.0.thanks to this confirmation from Seagate. That interface maxes out at around 3.75GB/s and so it's literally physically impossible to be getting 5GB/s from SSD to APU without using compression even if the drive itself wee capable of more than 2.4GB/s.
     
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  12. liams

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    maybe the decompression happens transparently to the game dev? so even though the drive is delivering 2.4 GB/s it's no different to the dev than a drive that's 4.8 GB/s? it could be that he's talking about once games start getting made for it they will be able to do affectively 5 GB/s, or thereabouts. Its very possible that codemasters have been playing around with the tech on internal demos just to get a feel for the tech and how best to implement things like SFS and the velocity architecture.
     
  13. QPlayer

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    Maybe the VA has a significant role to play in this.
     
  14. pjbliverpool

    pjbliverpool B3D Scallywag
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    I guess it is possible that he didn't even realise the data was compressed but I'd kinda expect a bit more from game Technical Director! He was pretty explicit in that he didn't think compression was being used:

    "And that was without the compression in the hardware, that was just raw."

    The Velocity Architecture is just the marketing name given to the XSX IO system that we're already discussing. We already understand pretty well how it works.
     
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  15. liams

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    Ah, I missed that quote.
    Maybe he was being generous with the '2 seconds'? if it was 2.9 seconds that would check out. Microsoft said that the 2.4 GB/s is the sustained performance, so I assume it can peak higher than that, so 10/2.9 = 3.44 GB/s ? Seems plausible
     
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  16. megre

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    If you send 5GB of compressed data (that goes through the ASIC block) in two seconds, you'll get 10GB of uncompressed data in 2 two seconds.

    Maybe that's all he's saying. But I don't know.
     
  17. pjbliverpool

    pjbliverpool B3D Scallywag
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    When they say sustained, I take them to mean that the drive can sustain it's peak throughput, probably due to robust cooling. The peak should just be a function of the memory speed and the controller. We know the controller is capable of 3.75GB/s but if it's using slower memory then the peak will be 2.4GB/s. However there's no reason if couldn't sustain that under the right operations if cooling is sufficient.
     
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  18. rntongo

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    The interface maxes out at 3.983GB/s. The E-19 controller maxes out at 3.75GB/s. The custom E-19 controller in the Series X has an extra asic such that it maxes out at 3.983GB/s. So its a highly custom SSD not like others that share the same controller. And the technical director for Dirt 5 was very clear when he said,

    "And that was without the compression in the hardware, that was just raw."

    So whatever figures he gave, with the decompression hardware it would perform better.

    Here's what I suspect, the SSD in the Series X can sustain 2.4GB/s constantly. But due to the custom controller and custom firmware it can go higher than this up to 3.983GB/s and maybe sometimes lower.

    But again, it would have been good if he had been pressed about whether the data was decompressed first or just sent to RAM immediately for testing purposes. If it was using the CPU for decompression, then its even more impressive because the decompression block can definitely do better.

    Thats why he gave the following statement:
    "it may well be able to do way better than that."
     
  19. rntongo

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    But according to him, it would be going through the pipeline without using the decompression algorithms from the decomp block(Maybe using the CPU?). And thats what makes it super impressive because it would mean with the decomp hw acceleration it can definitely outperform that.
     
  20. pjbliverpool

    pjbliverpool B3D Scallywag
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    I think you've misunderstood what that link was saying. The Western Digital SN530 is a 2.4GB/s SSD that uses a PCIe 3.0 (4x) interface. The custom ASIC used on the Xbox drive merely allows it to use a PCIe 4.0 (2x) interface instead (likely to make future expansion cards easier to manufacture).

    The drive speed is still the same at 2.4GB/s which is a factor of the controller and the memory speed. The controller is capable of 3.75GB/s if you pair it with the fastest compatible memory. The SN530 as uses in the Series X uses a slower tier of memory which gives you the 2.4GB/s. That's why Microsoft advertise it as such.

    The 3.983 GB/s is merely the theoretical max throughput of a PCIe 3.0 4x or PCIe 4.0 2x interface. You're still limited by the controller on the XSX to 3.75GB/s and then limited again by the memory connected to that controller to 2.4GB/s.
     
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