AMD: Navi Speculation, Rumours and Discussion [2017-2018]

Discussion in 'Architecture and Products' started by Jawed, Mar 23, 2016.

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  1. yuri

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    Reading into the last update given last week at the Deutsche Bank telco, it seems the Navi GPUs will be late. The roadmap given says 2018 for Vega 20, early 2019 7nm EPYC aka Rome and after that they will push the 7nm desktop CPUs/APUs. After all this is out of the house, they will release Navi. This doesn't seem to be a mid-2019 release TBH.
     
  2. Kaotik

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    I have no clue where WCCFTech gets their ideas, but AMD hasn't said or shown anything suggesting Navi wouldn't be GCN

    I know my memory isn't perfect, but I follow these closely (even for work) and can't remember seeing any such slides ever, nor did I find any suggesting such either.
    You sure you're not mixing it with the one that says "Scalability" and "Nexgen memory" on it?
     
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  3. Azhrei

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    In several presentation slides, AMD presented Navi as being before "Next Gen", so I'm guessing it's the final gasp of GCN before they bring out the successor, probably in 2020/21. As shown here -

    [​IMG]

    [​IMG]
     
  4. ImSpartacus

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    They almost certainly are.

    There are a couple relatively straightforward points that suggest that Navi 10 is a ~64CU ~150W 256-bit GDDR6 GPU and Navi 11 is roughly half of Navi 10.
    • Polaris 10 & 11 will be three years old next year and they both need to be replaced, especially Polaris 11 for use on mobile.
      • AMD doesn't have the R&D to do a full lineup refresh like Nvidia can. They use GPUs for about 3 years before replacing them.
    • GCN still has a 4 shader engine limit as of Vega, so it's just 64CU GPUs until then. Luckily, a 7nm "shrink" of Vega 10 would pretty much perfectly fit into 150W (roughly half of 300W), which is frighteningly convenient as that's Polaris 10's target.
      • Of course, AMD could change GCN to go past 4 shader engines, but they have their reasons for avoiding that for as long as possible. Anandtech inquired about this:
    • AMD loves selling 256-bit GDDR GPUs at the $200-300 space and the bandwidth math just works out perfectly for GDDR6.
      • 14Gbps GDDR6 is already seen in the new Turing GPUs. On a 256-bit bus, it would provide 448 GB/s, which is pretty close to the 484 GB/s that the 64CU Vega 64 needs. You assume some minor efficiency increases in necessary bandwidth (and/or slightly fewer than 64CUs) and you're perfect.
    • Finally, yields. 7nm yields initially won't be high enough for a large consumer die.
      • AMD survived in 2016 without a high end consumer GPU when they transitioned to 14nm. Why should we expect the 7nm transition to be any different?
     
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  5. Digidi

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    Compared to 2080ti the frontend of Vega is not bad. I will get the same Drawcall Limits like the 2080 ti in the API Overhead test.
     
  6. 3dilettante

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    The described functionality of the RT cores is along the lines of an offloading co-processor or semi-independent sequencer. It's not entirely clear how they are physically integrated relative to the SIMD units or other blocks, but their behavior sounds closer to a core than the SIMD lanes, and might be nearer the polymorph or texturing units.
    In that regard, perhaps AMD could benefit from exposing to the outside world a new sequencer domain in their SIMDs, like the texturing block which does a fair amount of computation on its own and runs on the far side of a set of data and command buses.
    The scalar unit as we know it is linked more tightly to the scheduling and flow control elements that likely had something similar in hardware pre-GCN, just not exposed to the programmer.
    Adding more such resources may allow more concurrency in non-vector work and take advantage of the elements in the pipeline that do things like coalesce accesses and handle long-latency fetch loops, while adding a level of programmability the RT cores lack, although this doesn't guarantee the compactness in hardware and may not play well with the much more confined caches in current GCN.

    Saying they have a vision of cloud computing and are working with Microsoft is corporate-speak. It doesn't indicate the scope of the work, what part of the console space it encompasses, or how much has actually been committed to.
    From https://seekingalpha.com/article/42...18-deutsche-bank-technology-conference?page=5 (some transcription irregularities, but the sentences in bold seem clear):

    In both cases, it's an executive that most likely does not want to speak for a partner, but also means they are not claiming that the consoles have been committed to be AMD hardware.
    Competing for a contract and working together with the console makers are also not exclusive. Projects of this scope can have a lot of cooperative work between a hardware vendor and the platform holders, and that cooperation in setting down a candidate design could broadly count as "working with" Microsoft or Sony even if it is rejected. AMD's EPYC processors might be part of the cloud infrastructure for a console that is all or in part not AMD, and a worse scenario is working with Sony or Microsoft on a framework for backward/forward compatibility with a different vendor's CPU and/or GPU.

    Possibly yes and no? Perhaps the most significant ISA change came with GCN3, where VI changed its encoding significantly for scalar memory writes, as well as data-parallel operations and sub-word addressing. Also, AMD touted Vega as the biggest jump ever, and probably had similar marketing of other transitions.


    One idea that came to mind is that with Nvidia's task and mesh shaders, both vendors have now offered a re-tooling of the geometry front end. There is some overlap of scope, and some of their decisions probably align because they are facing similar challenges. However, I think they also diverge in various parts in ways that may conflict. One of the vendors has gone ahead and committed to offering its new shaders with a more clear API extension for its methods, and the other vendor has for some reason let things drop. The possibility exists that even a functional NGG might be threatened if the design target it had was replaced due to outside factors.

    If Nvidia gets its way, however, there's going to be a path available for a significant fraction of those calls that would bypass that bottleneck.
     
  7. Megadrive1988

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    https://wccftech.com/amd-new-major-gpu-architecture-to-succeed-gcn-by-2020-2021/
     
  8. Ryan Smith

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    Correct.

    However it wouldn't be ideal to make it immediately outdated. So the question is whether AMD pulls another Polaris - a "quick" architecture update for the sub-$300 market - or if they want to invest more heavily in a new top-to-bottom stack and/or major new features.

    I could easily see them going either direction, so AMD is a very hard read right now. Especially as Vega Mobile remains AWOL.
     
  9. yuri

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    Yes, where is the Vega Mobile? It's been almost 10 months since Dr. Su held the chip on stage.

    One might think it was the original "Polaris replacement" - Vega 11 which got reevaluated at some point. Then it was probably tweaked towards mobile and then again reevaluated and killed? The last hope are notebooks slated for the Xmas season.
     
  10. itsmydamnation

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    I think Vega mobile is just the least financially attractive part for AMD and given that GF is capacity constrained already it doesn't make sense to produce it, especially if this China SOC in manufactured at GF. Could they sell vega mobile for much more then Polaris, even enough to offset the interposer and HBM?
     
  11. ToTTenTranz

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    I just hope AMD manages to keep their mouths shut until Navi actually releases, whenever that is.
    80% of the "disappointment" surrounding Vega came from all the stuff they blabbed about during those 6 months before release.


    Which ones?



    Vega 20 is a 1/2 FP64 throughput GPU, so Navi wouldn't completely replace it unless it has the same functionality.
    After all, AMD still has the 5 year-old Hawaii for the FP64 HPC market, despite the GPU being outdated as "consumer flagship" since Fiji 4 years ago.
     
    #671 ToTTenTranz, Sep 24, 2018
    Last edited: Sep 24, 2018
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  12. Garrett Weaving

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    Yeah, I probably messed up with Navi being non-GCN based. Here's to hoping we see it soon enough!
     
  13. Garrett Weaving

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    In fact, I did mess up! Here's the slide I remember seeing, it was Nextgen memory, not arch:

    [​IMG]

    Unfortunately, I can't edit my last post, probably because I'm a new member.
     
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  14. Kaotik

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    Not Nextgen but Nexgen! Must be one of their secret sauces :runaway:
     
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  15. Geeforcer

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    LOL, those of us who have been following AMD for a long time surely remember NexGen, who AMD acquired and sources K6 architecture from in mid 90s. This memory tech has been 25 years in the making!:shock:
     
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  16. Garrett Weaving

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    Hahaha, indeed! Did anybody have the pleasure of using an Nx586 CPU?
     
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  17. A1xLLcqAgt0qc2RyMz0y

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    Funny seeing that picture where Navi was to be released at the end of 2017. Isn't the time frame for Navi mid 2019 now? So 18 months late.
     
  18. Garrett Weaving

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    To me it looks like Navi was supposed to come out sometime during 2018, possibly early 2018, since Polaris came out in mid 2016 and that is reflected by the slide.
     
  19. Geeforcer

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    Using Polaris as a reference point, Vega was due early 2017 and Navi a year later, early 2018, provided that these are supposed to be to scale.
     
  20. yuri

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    Yes, this seems plausible. The Greenland chip aka Vega 10 was mentioned numerous times along with the Polaris chips. Thus Vega should have originally launched much early.
     
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