Knights Landing CPU Speculation

Article: Knights Landing CPU Speculation
By: Patrick Chase (, November 23, 2013 4:33 pm
Room: Moderated Discussions
As always I agree with the *vast* majority of what Linus says, so I'll take the liberty of just snipping out the portions where I diverge.

Linus Torvalds ( on November 21, 2013 3:12 pm wrote:
> Amiba Gelos ( on November 19, 2013 8:36 pm wrote:
> >
> >
> > Second, I wonder whether the claim that Knights Landing is bootable really implies we need good scalar
> > core. A major advantage of bootable accelerator is that by
> > moving from a heterogeneous MP to SMP the programming
> > paradigm is greatly simplified. Therefore, faster scalar execution is not really needed.
> People definitely need faster scalar execution.
> Guys, don't look at just DGEMM benchmarks or pure "throughput" stuff. The real HPC
> market cares deeply about things like "sufficient NFS client performance" for example,
> because in reality, that's how most of those clusters end up doing a lot of the data
> distribution.

Most real HPC systems have dedicated I/O nodes for that sort of thing, whether it be the Xeon/Opteron in "Xeon/Opteron + Tesla/Phi", or dedicated cores in BG/Q systems. That isn't really a reason to constrain the architecture of the *compute* nodes.

> Prediction: the whole PCIe card model will die, very much due to this kind of
> pressure.

The reason why the PCIe card model exists at all is economics: Discrete PCIe GPUs were being designed anyway for a much more lucrative market, and the HPC guys got to go along for the ride (albeit at the cost of the development hassles that you describe).

I therefore think that its death or lack thereof will be very much a function of how the graphics market evolves. If discrete GPUs die (or at least become such a small niche that the economies of scale vanish) then I think you'll be prove right, but not for the reasons you cite.
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TopicPosted ByDate
Knights Landing CPU SpeculationDavid Kanter2013/11/18 03:03 AM
  Knights Landing CPU Speculationnone2013/11/18 03:59 AM
    Knights Landing CPU SpeculationPatrick Chase2013/11/23 04:18 PM
      Knights Landing CPU SpeculationAdam Kalisz2013/11/26 02:20 AM
        Over 2,000 mm^2 of eDRAM???Mark Roulo2013/11/26 10:28 AM
          Over 2,000 mm^2 of eDRAM???David Kanter2013/11/26 12:09 PM
          Over 2,000 mm^2 of eDRAM???Eric Bron2013/11/26 12:21 PM
            Over 2,000 mm^2 of eDRAM???tarlinian2013/11/26 12:50 PM
              Over 2,000 mm^2 of eDRAM???Eric Bron2013/11/26 02:07 PM
                Over 2,000 mm^2 of eDRAM???Eric Bron2013/11/26 02:09 PM
                Over 2,000 mm^2 of eDRAM???aaron spink2013/11/26 04:03 PM
                  Over 2,000 mm^2 of eDRAM???Eric Bron2013/11/27 12:42 AM
                    Over 2,000 mm^2 of eDRAM???aaron spink2013/11/27 11:31 AM
              Over 2,000 mm^2 of eDRAM???David Kanter2013/11/26 05:25 PM
                Over 2,000 mm^2 of eDRAM???tarlinian2013/11/26 08:01 PM
          Over 2,000 mm^2 of eDRAM???Eric2013/11/27 03:54 AM
            eDRAM is DRAM in a logic-oriented processPaul A. Clayton2013/11/27 08:10 AM
  Knights Landing CPU SpeculationJames2013/11/18 06:26 AM
    Knights Landing CPU SpeculationMichael S2013/11/18 03:57 PM
      Knights Landing CPU SpeculationUrban Novak2013/11/19 01:49 AM
        Knights Landing CPU Speculationnone2013/11/19 02:19 AM
          Knights Landing CPU SpeculationEric2013/11/19 08:48 PM
            Total GPGPU/Xeon Phi market maybe ~ $500M/year ...Mark Roulo2013/11/20 11:35 AM
      Knights Landing CPU SpeculationWes Felter2013/11/19 01:06 PM
        Knights Landing CPU SpeculationMichael S2013/11/19 01:49 PM
  Knights Landing CPU SpeculationEric2013/11/18 01:17 PM
    Knights Landing CPU SpeculationDaniel2013/11/19 03:28 AM
      Knights Landing CPU SpeculationEric2013/11/19 08:36 PM
      HPC guys score FLOPS non-obviouslyMark Roulo2013/11/20 11:43 AM
        3-TFlops-DGEMMMichael S2013/11/20 11:59 AM
          3-TFlops-DGEMMMark Roulo2013/11/20 01:22 PM
            3-TFlops-DGEMMDaniel2013/11/20 02:04 PM
              3-TFlops-DGEMMEric2013/11/21 02:28 AM
                3-TFlops-DGEMMMichael S2013/11/21 06:48 AM
                  3-TFlops-DGEMMRecessionCone2013/11/21 12:13 PM
                    3-TFlops-DGEMMMichael S2013/11/21 03:34 PM
                  3-TFlops-DGEMMEric2013/11/22 03:10 AM
                    3-TFlops-DGEMMMichael S2013/11/22 05:41 AM
                    A (not very sensible) alternative: FMADD + FADDPaul A. Clayton2013/11/22 09:19 AM
                  3-TFlops-DGEMMSylvain Collange2013/11/24 03:37 AM
                    3-TFlops-DGEMMMichael S2013/11/24 07:06 AM
                      3-TFlops-DGEMMSylvain Collange2013/11/24 10:28 AM
        HPC guys score FLOPS non-obviouslyPatrick Chase2013/11/23 03:58 PM
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    Knights Landing CPU SpeculationKonrad Schwarz2013/11/19 01:24 AM
  Knights Landing CPU SpeculationAmiba Gelos2013/11/19 08:36 PM
    Knights Landing CPU SpeculationDavid Kanter2013/11/20 10:52 AM
    Knights Landing CPU SpeculationLinus Torvalds2013/11/21 03:12 PM
      Knights Landing CPU SpeculationAmiba Gelos2013/11/21 06:14 PM
      Knights Landing CPU SpeculationPatrick Chase2013/11/23 04:33 PM
        Knights Landing CPU SpeculationLinus Torvalds2013/11/25 12:29 PM
          Knights Landing CPU SpeculationLinus Torvalds2013/11/25 01:05 PM
          Knights Landing CPU SpeculationPatrick Chase2013/11/25 01:22 PM
            Knights Landing CPU SpeculationLinus Torvalds2013/11/26 11:11 AM
          Knights Landing CPU SpeculationEric2013/11/26 04:05 AM
            Knights Landing CPU SpeculationEric2013/11/26 04:15 AM
            Knights Landing CPU Speculationnone2013/11/26 04:33 AM
              Knights Landing CPU SpeculationEric2013/11/26 07:30 PM
                Knights Landing CPU SpeculationEric2013/11/26 07:34 PM
                  What is MCDRAM?anon2013/11/26 09:58 PM
                    What is MCDRAM?none2013/11/27 02:00 AM
                      What is MCDRAM?Klimax2013/11/27 03:19 AM
                  Knights Landing CPU SpeculationKlimax2013/11/27 12:06 AM
                Knights Landing CPU SpeculationKlimax2013/11/27 12:05 AM
            Knights Landing CPU Speculationanon2013/11/26 06:53 AM
              Knights Landing CPU Speculationnone2013/11/26 07:20 AM
                Knights Landing CPU SpeculationMichael S2013/11/26 09:06 AM
                  Knights Landing CPU Speculationnone2013/11/26 10:18 AM
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                      Knights Landing CPU SpeculationEric Bron2013/11/26 02:27 PM
                        Knights Landing CPU Speculationnone2013/11/26 03:26 PM
                    Knights Landing CPU Speculationanon2013/11/26 06:42 PM
                      Knights Landing CPU Speculationnone2013/11/27 02:08 AM
                        Knights Landing CPU Speculationanon2013/11/27 02:50 AM
                          Knights Landing CPU Speculationnone2013/11/27 02:58 AM
                      Knights Landing CPU SpeculationMichael S2013/11/27 02:25 AM
                        Knights Landing CPU Speculationanon2013/11/27 03:32 AM
                          Knights Landing CPU SpeculationMichael S2013/11/27 04:08 AM
    Knights Landing CPU SpeculationChung Leong2013/11/27 02:28 AM
      Knights Landing CPU SpeculationMichael S2013/11/27 03:53 AM
        Knights Landing CPU SpeculationChung Leong2013/11/27 02:03 PM
  BiG.LiTTLe for KNL?Jeff K2013/11/22 07:17 AM
    BiG.LiTTLe for KNL?Patrick Chase2013/11/23 03:54 PM
      BiG.LiTTLe for KNL?Patrick Chase2013/11/23 04:01 PM
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      Transactional memoryPatrick Chase2013/11/25 12:52 PM
  Knights Landing CPU SpeculationDaniel2013/11/25 03:17 AM
    Knights Landing CPU SpeculationKlimax2013/11/25 04:12 AM
    Knights Landing CPU Speculationnone2013/11/25 05:05 AM
      Knights Landing CPU SpeculationKlimax2013/11/25 05:45 AM
        Knights Landing CPU Speculationnone2013/11/25 05:55 AM
          Knights Landing CPU Speculationgmb2013/11/25 08:21 AM
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