Knights Landing CPU Speculation

Article: Knights Landing CPU Speculation
By: anon (anon.delete@this.anon.com), November 27, 2013 2:50 am
Room: Moderated Discussions
none (none.delete@this.none.com) on November 27, 2013 2:08 am wrote:
> anon (anon.delete@this.anon.com) on November 26, 2013 6:42 pm wrote:
> > none (none.delete@this.none.com) on November 26, 2013 10:18 am wrote:
> > > Michael S (already5chosen.delete@this.yahoo.com) on November 26, 2013 9:06 am wrote:
> > > > none (none.delete@this.none.com) on November 26, 2013 7:20 am wrote:
> > > > > anon (anon.delete@this.anon.com) on November 26, 2013 6:53 am wrote:
> > > > > > Eric (eric.kjellen.delete@this.gmail.com) on November 26, 2013 4:05 am wrote:
> > > > > > > Linus Torvalds (torvalds.delete@this.linux-foundation.org) on November 25, 2013 12:29 pm wrote:
> > > > > > > > And the old Atom really was pretty bad at some general-purpose stuff. That VR-zone link
> > > > > > > > says KNL is 72 modified Silvermont cores, so it should be much better in that regard.
> > > > > > > >
> > > > > > > > Linus
> > > > > > >
> > > > > > > What I am mostly interested in is exactly how they are modified
> > > > > > > with regard to vector processing. The Knights
> > > > > > > Corner cores and those of its predecessors were basically P54C derivatives with an added 512-bit vector
> > > > > > > unit (for 16 DP FMA flops per core and cycle) but as we
> > > > > > > speculated in a different branch of the thread (what
> > > > > > > is now "3-TFLOPS-DGEMM") 72 Silvermont cores with a single 512-bit vector unit will not be enough to give
> > > > > > > the cited 3 DP peak TFLOPS at a reasonable clock frequency (they would have to run at 2.6 GHz).
> > > > > >
> > > > > > Why is 2.6GHz an unreasonable frequency?
> > > > > >
> > > > > > Intel's 14nm silvermont derivative is reported to have 2.7GHz clock.
> > > > >
> > > > > Try to put 72 of them along with 2 wide vector units and you'll see that doesn't seem
> > > > > reasonable even on 14nm :-)
> > > >
> > > > Yes, judged by Avaton C2750, when running at max. frequency 72
> > > > Silvermont cores alone, without VPUs, would eat over 150W.
> >
> > How do you calculate that? Compare between C2550 and C2750, and you add 6W TDP for 4
> > cores (plus 2MB L3, inteconnect, etc, but ignore that). Then reduce power by 30% for
> > 14nm. That comes out at 1.05W per core at 2.4GHz (presumably). Increase frequency to
> > 2.6 probably brings power up significantly, but it seems 72 cores could fit into 100W.
>
> You think the VPU won't come with increased power?

No.

> Do you know that on Haswell as soon
> as the AVX unit gets used voltage is increased (at least that's what happen on my
> system)? Have you ever seen Haswell power consumption skyrocket as soon as AVX is
> heavily used? And that's with a 256-bit SIMD unit.
>
> Then you have to add eDRAM, interconnect, etc.
>
> > > > But why did you mention "2 wide vector units"? At 2.7 GHz one unit per core will do the job.
> > >
> > > You're right. But current rumors point to Silvermont + dual VPU, so in that context
> > > saying 14nm next gen Atom can reach 2.7 GHz kind of assumes these rumors are correct,
> > > so 2 VPUs :-)
> >
> > No it doesn't! The whole point is to derive how they can achieve
> > 3 TFLOPS. If it runs at 2.6GHz, then it requires 1 vector unit.
>
> OK, if you insist, but IMHO that still won't fit.

Ok, then what are your estimates?
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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 Speculation2013/11/26 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
  Knights Landing CPU SpeculationPaul Caheny2013/11/18 02:25 PM
    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
                    Knights Landing CPU SpeculationEric Bron2013/11/26 02:21 PM
                      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
  Transactional memoryPatrick Chase2013/11/23 03:37 PM
    Transactional memoryBhima2013/11/25 08:01 AM
      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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