Knights Landing CPU Speculation

Article: Knights Landing CPU Speculation
By: anon (anon.delete@this.anon.com), November 27, 2013 3:32 am
Room: Moderated Discussions
Michael S (already5chosen.delete@this.yahoo.com) on November 27, 2013 2:25 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).
>
> I don't agree with that approach, for 2 reasons:
>
> 1. I don't know what C2550 physically is. Is it the same die as C2730/C2750 or the same die as Bay Trail
> or neither first nor second? Most likely the answer is "the same die as as C2730/C2750". So it's suboptimal
> by design. Now the next question - are unused cores powered off? I hope yes, but does it make them free
> from power stand point? I personally don't see why not, but I don't know nearly enough.
>
> 2. Marketing.
> C2550 should not be too attractive. Otherwise it would be too efficient internal competitor to both C2730
> (say, in SOHO servers) and to J2850/J1900 in SBCs and other products that do not care about graphics. May
> be, even to E3-1220L v3, although this one probably don't need internal competition to sell poorly.
> So, there are little reasons for Intel to qualify it for absolutely lowest possible TDP. If it
> was important for them, I'd guess that technically they will be capable to split C2730 into two
> SKUs, one with TDP of 14W and the other, slightly more expensive, with TDP of 10 or 11W.
>
>
> I prefer to compare C2750 with C2730 (TDP increase of 1W per core).
> Of course the data is insufficient for an ultimate conclusion, but my estimate 2.0-2.2W
> per core at 2.4 GHz (22nm) appear closer to reality than your suggestion of 1.5W.

Maybe, but comparing C2530 with C2550 gives more than 1W per core increase, so there seem to be other components adding to the power increase as well.

>
> > Then reduce power by 30% for 14nm.
>
> Sounds optimistic.

This is what Intel quotes.

>
> > 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.
> >
>
> Which still too high, considering 200W TDP for the whole chip.

How much would wider vector units add, in your estimate?

How would the power breakdown fit if there are 1.3GHz clocked cores?

>
>
> > > > 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.
< Previous Post in ThreadNext Post in Thread >
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
Reply to this Topic
Name:
Email:
Topic:
Body: No Text
How do you spell green?