AMD Radeon VII Announcement and Discussion

Discussion in 'Architecture and Products' started by ToTTenTranz, Jan 9, 2019.

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  1. mrcorbo

    mrcorbo Foo Fighter
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    Which applies to the 8GB Vega cards. HBCC is in Radeon VII because it is in Vega 20. HBCC won't be too useful in a gaming card with 16GB of RAM, but it is useful in other configurations and uses for the chips. It could also be VERY useful for consoles, which have a relatively limited memory pool.
     
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  2. DmitryKo

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    "High Bandwidth Cache Controller" is AMD's marketing term for their crossbar memory/cache/Infinity Fabric controller, so they cannot remove it from the chip.

    HBCC uses additional page tables in virtual memory hierarchy to support 49-bit virtual addressing with 4K and 2M page sizes, and to detect and automatically unload unused memory pages from local memory.

    This is similar to Direct3D11.2 "tiled resources" (sparse textures) where large data resources are paged in on-demand, which also was a specific implementation of memory paging, but working under explicit developer control over page tables and residency behavior (see Build 2013 session 4-063). This time it's like forced "automatic tiled resources" under explicit control of the video memory manager.

    Direct interface to local NVRAM (to avoid PCIe transfers from system memory) is intended for Radeon Pro SSG-class professional products which have 2TB of non-volatile storage.


    They say NGG was supposed to work a with existing APIs through driver-level translation, but unspecified performance/optimization issues arose which required explicit support for this combined vertex/domain/geometry stage in high-end APIs like D3D12/Vulkan, and then implementation efforts were stopped for the Vega architecture. That's all we know so far.
     
    #102 DmitryKo, Jan 10, 2019
    Last edited: Jan 11, 2019
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  3. Rootax

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    Because it's still faster to have the assets in the vram, and I guess they wanted 16gb on the box to looked good compared to existing products...
     
  4. mrcorbo

    mrcorbo Foo Fighter
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    Why are you having so many difficulties understanding this? It was touted as benefiting games on an 8GB card when game had memory requirements that tested that limit. On a 16GB, this probably won't happen. The HBCC has many applications in Vega, so it's going to be in there whether a specific configuration is able to benefit from it or not.
     
    #104 mrcorbo, Jan 10, 2019
    Last edited: Jan 10, 2019
  5. Malo

    Malo Yak Mechanicum
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    On a test from a year ago with older Vega cards and simply to showcase the technology in games where you could be VRAM limited. You specifically questioned the technology in relation to 16Gb Vega 20 cards in which I provided other use cases where it was really designed for.
     
  6. Ike Turner

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    Don't feed the tro...
     
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  7. Arun

    Arun Unknown.
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    I suspect the economics depend a lot on the relative volumes of the Radeon Instinct server SKU... If only a small % of chips meet the spec for the Radeon Instinct but many more meet the Radeon VII's specs (not just 60 vs 64 CUs but also power/leakage/etc.) then the cost doesn't really matter, since it's always better than letting those chips go to waste.

    That might mean the Radeon VII will be supply limited though, if it's only profitable if the demand for the Radeon Instinct is high enough to only sell "rejects" rather than fully enabled chips... Either way I think it's a very good decision for AMD to release it at $699.
     
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  8. BoMbY

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    If the yields would be abyssal, there probably wouldn't be a Radeon VII. Also why not use 56 CUs variants at all so far, if the yields are that bad? 6.2 TFlop/s DP would still be good for compute-only cards.
     
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  9. Arun

    Arun Unknown.
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    BTW - those graphs are theoretically correct but misleading as they don't show how the cost reduces over time. You could find similar graphs for nearly all processes in the last 10-20 years showing a sudden jump in cost for the latest and greatest...

    The reality is that new processes are always: 1) very expensive, 2) very defect-prone, 3) very R&D intensive. But after a few years, the cost drops as the equipment is amortised, the yields become really good, and all the tools improve. So those graphs are misleading because they compare mature processes to leading-edge processes.

    I think a fair comparison for "normalized cost/yielded mm" would be at "X years after start of risk production" (e.g. 3 years) - if you did that, I suspect you'd see a lot less dramatic increase for 7nm. Of course the *current* cost still matters to decide what process to manufacture a chip on and how competitive a product is; and in that case, the leading-edge process is indeed a lot more expensive in every way. And yes, every process is more expensive than the last, and maybe 7nm will be uniquely much more so even after it matures... but it's probably fine.
     
  10. Arun

    Arun Unknown.
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    Agreed but if you're going for even more redundancy, it might make sense to go for 96 ROPs/3072-bit memory bus rather than 128 ROPs/4096-bit (remember it's going to be a significantly higher % of the chip than on 14nm Vega since the memory bus is wider and I/O doesn't scale as much as logic if at all). But at that point the performance might be too low to be competitive and/or attractive, so maybe it'd make the most sense as a special SKU for specific OEMs and/or HPC/AI customers...
     
  11. Rootax

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    Have we a confirmation avoir 128 rop / tmu ?
     
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  12. yuri

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  13. Rootax

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    Ok so only anandtech is talking about 128rop/tmu. If it has still 64 (or 60), I'm sure the benchs they used were very bandwidth bound. But in most situations, I don't see a big jump over a well cooled Vega64...

    Meh. Where is Navi...
     
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  14. mrcorbo

    mrcorbo Foo Fighter
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    Not everything is the best/worst. Not everyone is for/against. Pointing out where one criticism isn't valid doesn't indicate a belief that all criticisms are invalid.
     
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  15. silent_guy

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    Are you talking Nvidia or AMD here?

    Because I don’t think Vega VII counts as a competitive product.

    “Underwhelming” is almost too kind.
     
  16. silent_guy

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    It’s almost as if you believe this to be an unrealistic scenario.
     
  17. silent_guy

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    Exactly. It’s pointless to talk about profit in this case, and much more meaningful to use gross margin. Radeon VII will increase those for very low additional effort. It’s a no-brainer to release this underwhelming GPU.
     
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  18. Malo

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    Well Ryan talks about the 128 ROPs in the article itself, not just mentioned in the specs so one would think @Ryan Smith has obtained accurate information.
     
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  19. Rootax

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    But, If i'm not mistaken, even mi-50/60 don't have that. And I don't see amd making a new gpu. Adding rop is not a small task...
     
  20. itsmydamnation

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    Extraordinary claims require extraordinary proof.
     
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