Velocity Architecture - more than 100GB available for game assets

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

  1. tinokun

    Newcomer Subscriber

    Joined:
    Jul 23, 2004
    Messages:
    60
    Likes Received:
    67
    Location:
    Peru
    Yes, it's just a coincidence; read BRiT's post above.
     
  2. BRiT

    BRiT Verified (╯°□°)╯
    Moderator Legend Alpha

    Joined:
    Feb 7, 2002
    Messages:
    16,020
    Likes Received:
    15,010
    Location:
    Cleveland
    It was said that 6 GB/s is a conservative estimate using typical compression levels. Perhaps one of those Twitter discussion threads.
     
    PSman1700 likes this.
  3. Metal_Spirit

    Regular Newcomer

    Joined:
    Jan 3, 2007
    Messages:
    558
    Likes Received:
    341
    How???
    How do you compress textures without reading them uncompressed?
    And if you are reading them uncompressed, what's the use of compressing them if they are already in memory?
     
  4. BRiT

    BRiT Verified (╯°□°)╯
    Moderator Legend Alpha

    Joined:
    Feb 7, 2002
    Messages:
    16,020
    Likes Received:
    15,010
    Location:
    Cleveland
    Those numbers are for illustrative and comparative purposes if you were doing things without one aspect or another being used.

    For the illustration of how the techniques combine I provided 3 different scenarios.

    Scenario A) Developer did not use compression or SFS
    Scenario B) Developer only used compression
    Scenario C) Developer used compression and SFS

    In real world games, the developer should never use Scenario A. They would always have the textures compressed and packed. So games would fall under Scenario B or C.

    The game would also have textures already compressed, where it is packed into small chunk sizes. I believe from a developer Twitter discussion we know that the segment/chunk size is around 64K. So if the GPU determines it only requires access to 10 segments out of a 64 segment Texture, then only those 10 segments need to be read and not all 64.

    In Scenario B, all 64 segments would be read in [4 Meg].
    In Scenario C, only the needed 10 segments would be read in. [640K]
     
    PSman1700, tinokun and TheAlSpark like this.
  5. TheAlSpark

    TheAlSpark Moderator
    Moderator Legend

    Joined:
    Feb 29, 2004
    Messages:
    21,757
    Likes Received:
    7,446
    Location:
    ಠ_ಠ
    I'm not sure I understand the question.

    You would have compressed data that you transfer then process/decompress in memory.
     
    PSman1700 and tinokun like this.
  6. disco_

    Newcomer

    Joined:
    Jan 4, 2020
    Messages:
    246
    Likes Received:
    189
    That convo with the guy in charge of bcpack and the discussion that followed it? I was under the impression the outcome of that discussion was that bcpack allowed it to reach 1:1 compression and i/o got it to 2.5x.
     
  7. BRiT

    BRiT Verified (╯°□°)╯
    Moderator Legend Alpha

    Joined:
    Feb 7, 2002
    Messages:
    16,020
    Likes Received:
    15,010
    Location:
    Cleveland
    No. There was a different convo talking about decompression limits.

    And naturally I can't find it despite searching. :(
     
    #107 BRiT, Jul 27, 2020
    Last edited: Jul 27, 2020
    disco_ likes this.
  8. Metal_Spirit

    Regular Newcomer

    Joined:
    Jan 3, 2007
    Messages:
    558
    Likes Received:
    341
    First an explanation. What I'm describing is what the YouTube channel XboxBr explained as beeing the way the Velocity Engine works.
    SFS and its ID buffers connected to the GPU and the 100 GB virtual RAM Partition that would hold uncompressed textures as if they were in RAM.
    Was the explanation correct? Dont know, and that is why I'm questioning, because if it is, I dont see it working on compressed texture data.

    That is why I placed the question.
    The explanation seemed logic to me since SFS is a GPU feature, and as such works with GPU memory, and this partitition is meant to to work as virtual memory, keeping data on the same state as if it was on real RAM.
    As such, this can give effective gains by only supplying (reading) the required part of the the textures to the GPU real RAM.
    But if the system works like that, it seems to pose a question. Can these gains be applyed to compressed data?
    Because to compress data you would have to read the uncompressed data to RAM, and this would kill the need for compression since data would already be in RAM and the SSD transfer capacity already used. Besides these compressors in hardware are able to decompress in real time. But can they compress with the same efficiency? And can they compress and decompress in sequence keeping things in real time?

    As I see it, the gains can only be applyed to uncompressed data. And this was why I questioned. So that if I what was explained is wrong, or if what I understood is wrong someone could explain me the process
     
  9. disco_

    Newcomer

    Joined:
    Jan 4, 2020
    Messages:
    246
    Likes Received:
    189
    No worries.
     
  10. Silent_Buddha

    Legend

    Joined:
    Mar 13, 2007
    Messages:
    17,098
    Likes Received:
    6,457
    You would need way more than 100 GBs for textures if they were stored uncompressed. Like WAAAAAY more.

    Regards,
    SB
     
    tinokun and function like this.
  11. Allandor

    Regular Newcomer

    Joined:
    Oct 6, 2013
    Messages:
    386
    Likes Received:
    192
    depends on the textures and the game :mrgreen:

    But yes, you are right. Also we should distinguish between texture and data-compression. Texture compression is the same on on the storage like in memory. Data compression is a general purpose compression, before the data can be used it must be decompressed.
    Well.. ok, there are also texture compression formats that are just data compressions just optimized for textures but I count that to the data compression.
     
    function likes this.
  12. Silent_Buddha

    Legend

    Joined:
    Mar 13, 2007
    Messages:
    17,098
    Likes Received:
    6,457
    Of course. :) A small indie game likely doesn't have over 100 GB of uncompressed texture, whether in specific texture compression formats or otherwise.

    Imagine something like RDR2 without any compression for its texture set. :shock:

    Regards,
    SB
     
    #112 Silent_Buddha, Jul 28, 2020
    Last edited: Jul 28, 2020
  13. function

    function None functional
    Legend Veteran

    Joined:
    Mar 27, 2003
    Messages:
    5,367
    Likes Received:
    2,876
    Location:
    Wrong thread
    Pretty sure it's not a separate partition. Willing to bet on that actually! I'm also expecting that you read can this data from the game install, compressed.

    SFS seems to work at the level of a mip-page (a sampler miss from the page triggers its loading), and that makes a great deal of sense including in how you use the SSD efficiently. Fetching a compressed page (at least at the level of DXTC, hopefully supporting BCPack too) is actually what you want in terms of speed and BW used, and that seems to be exactly what XSX is set up to offer.

    Hopefully we'll find out more at Hotchips, but so far it looks like MS are working along the lines of accelerating access to "100GB" of assets in the install. And that should, I think, support various levels of compression (DXTC etc on the GPU, LZ and BCPack on the SSD IO block).
     
    tinokun, BRiT and disco_ like this.
  14. BRiT

    BRiT Verified (╯°□°)╯
    Moderator Legend Alpha

    Joined:
    Feb 7, 2002
    Messages:
    16,020
    Likes Received:
    15,010
    Location:
    Cleveland
    It is not limited to 100 GB. We've covered this in the tech threads a couple weeks ago when the Xbox Blogs and Videos were released.

    It's reasonable to assume it's not a separate partition because of that.
     
    tinokun likes this.
  15. rntongo

    Newcomer

    Joined:
    May 23, 2020
    Messages:
    11
    Likes Received:
    7
    I saw that tweet. He said the 4.8GB/s figure was conservative. The actual effective throughput will be higher than this. And Andrew Goossen did say it's over 6GB/s in the Eurogamer interview.
     
    PSman1700 and BRiT like this.
  16. t0mb3rt

    Joined:
    Jun 8, 2020
    Messages:
    8
    Likes Received:
    8
    So, I remember reading somewhere (but I can't find it for the life of me) that the XSX reserves 200MB (at least I think I read 200MB) of the "fast" RAM for the OS in addition to the 2.5GB of "slow RAM".

    Could that have anything to do with this? Unless I'm crazy... but I swear I read that somewhere.
     
  17. BRiT

    BRiT Verified (╯°□°)╯
    Moderator Legend Alpha

    Joined:
    Feb 7, 2002
    Messages:
    16,020
    Likes Received:
    15,010
    Location:
    Cleveland
    Its only 32 Meg. It's used for video compositing of dashboard notifications like achievements popups or friends login or message received or the guide overlay or even the full dashboard screens.

    https://forum.beyond3d.com/threads/...ne-x-and-xbox-series-x-2019-12-2020-03.61513/
    https://forum.beyond3d.com/threads/...lease-holiday-2020.61502/page-22#post-2139858
     
  18. t0mb3rt

    Joined:
    Jun 8, 2020
    Messages:
    8
    Likes Received:
    8
  19. Metal_Spirit

    Regular Newcomer

    Joined:
    Jan 3, 2007
    Messages:
    558
    Likes Received:
    341
    I was holding on adding more data because I could not find the video in question (they changed the name).
    The channel is XboxBr, and they clain to be an official Xbox Channel.

    I leave the video link (it’s in Portuguese)


    The diagram they show is this

    [​IMG]

    As I mentioned, they refer to the 100 GB as a place where textures are uncompressed, hence the reference to the remain of the SSD as “dados compactados”, or compressed data.
    SFS only gets data from this, not anywhere else, and that was why I questioned you about how compressed data could gain, since there would be no gain in SSD speed in compression because reads would have to be uncompressed.

    I do not know if this diagram is correct, but the video is online, and they claim to be an official Xbox channel.
     
    #119 Metal_Spirit, Aug 3, 2020
    Last edited: Aug 3, 2020
    pjbliverpool likes this.
  20. chris1515

    Veteran Regular

    Joined:
    Jul 24, 2005
    Messages:
    4,786
    Likes Received:
    3,744
    Location:
    Barcelona Spain
    James Stanard tôle 4.8 GB/s is conservative. a bit over 6GB/s is the limit of the hardware decompressor.
     
Loading...

Share This Page

  • About Us

    Beyond3D has been around for over a decade and prides itself on being the best place on the web for in-depth, technically-driven discussion and analysis of 3D graphics hardware. If you love pixels and transistors, you've come to the right place!

    Beyond3D is proudly published by GPU Tools Ltd.
Loading...