Why no EMIB?

By: Jeff S. (fakity.delete@this.fake.com), November 7, 2018 9:45 am
Room: Moderated Discussions
anon.1 (abc.delete@this.def.com) on November 7, 2018 7:00 am wrote:
> Kevin G (kevin.delete@this.cubitdesigns.com) on November 6, 2018 8:06 am wrote:

> > Leveraging EMIB for a PCIe 8x link between the Vega GPU and Kaby Lake die would
> > not have been a wise decision as it would not have brought performance increase
> > or significant power consumption decreases. It would still have been an 8x link.

> Ah, you're right, I forgot about Stratix. Re. EMIB/interposer, I thought the whole point of the thing
> was you go wider but slower. Data transfer rate stays the same but power goes down. That was AMD argument
> in a hotchips presentation in favor of HBM instead of GDDR. Does the same logic not apply? Thanks!

Cross-substrate transfers apparently cost around 2 pJ/bit vs. 0.3-ish over passive interposers (as measured by actually consumed bandwidth, not link capacity). The question then becomes how much you are willing to pay for development and validation/integration costs to save maybe a Watt or two per link that only in incurred under the heaviest transfer scenarios, which are likely to be transient conditions for all but a small subset of users' applications. HBM makes more sense since each module can transfer around 250 GB/s already (and twice again that for HBM3) that is likely to be close to fully saturated, where an Infinity Fabric link is around 50 GB/s and will have very low duty cycles for many workloads.
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TopicPosted ByDate
Why no EMIB?dmcq2018/11/06 03:45 AM
  Why no EMIB?anon2018/11/06 04:31 AM
    Why no EMIB?anon.12018/11/06 08:15 AM
      Why no EMIB?Kevin G2018/11/06 09:06 AM
        Why no EMIB?useruser2018/11/06 10:41 AM
        Why no EMIB?anon.12018/11/07 08:00 AM
          Why no EMIB?Jeff S.2018/11/07 09:45 AM
      Why no EMIB?David Hess2018/11/09 09:43 PM
        Why no EMIB?dmcq2018/11/10 07:35 AM
          Why no EMIB?Maynard Handley2018/11/10 09:27 AM
          Why no EMIB?David Hess2018/11/10 09:37 AM
  TTMDaniel B2018/11/06 02:21 PM
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