Article: Knights Landing CPU Speculation
By: anon (anon.delete@this.anon.com), November 27, 2013 1:50 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?
> 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?
Topic | Posted By | Date |
---|---|---|
Knights Landing CPU Speculation | David Kanter | 2013/11/18 02:03 AM |
Knights Landing CPU Speculation | none | 2013/11/18 02:59 AM |
Knights Landing CPU Speculation | Patrick Chase | 2013/11/23 03:18 PM |
Knights Landing CPU Speculation | 2013/11/26 01:20 AM | |
Over 2,000 mm^2 of eDRAM??? | Mark Roulo | 2013/11/26 09:28 AM |
Over 2,000 mm^2 of eDRAM??? | David Kanter | 2013/11/26 11:09 AM |
Over 2,000 mm^2 of eDRAM??? | Eric Bron | 2013/11/26 11:21 AM |
Over 2,000 mm^2 of eDRAM??? | tarlinian | 2013/11/26 11:50 AM |
Over 2,000 mm^2 of eDRAM??? | Eric Bron | 2013/11/26 01:07 PM |
Over 2,000 mm^2 of eDRAM??? | Eric Bron | 2013/11/26 01:09 PM |
Over 2,000 mm^2 of eDRAM??? | aaron spink | 2013/11/26 03:03 PM |
Over 2,000 mm^2 of eDRAM??? | Eric Bron | 2013/11/26 11:42 PM |
Over 2,000 mm^2 of eDRAM??? | aaron spink | 2013/11/27 10:31 AM |
Over 2,000 mm^2 of eDRAM??? | David Kanter | 2013/11/26 04:25 PM |
Over 2,000 mm^2 of eDRAM??? | tarlinian | 2013/11/26 07:01 PM |
Over 2,000 mm^2 of eDRAM??? | Eric | 2013/11/27 02:54 AM |
eDRAM is DRAM in a logic-oriented process | Paul A. Clayton | 2013/11/27 07:10 AM |
Knights Landing CPU Speculation | James | 2013/11/18 05:26 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/18 02:57 PM |
Knights Landing CPU Speculation | Urban Novak | 2013/11/19 12:49 AM |
Knights Landing CPU Speculation | none | 2013/11/19 01:19 AM |
Knights Landing CPU Speculation | Eric | 2013/11/19 07:48 PM |
Total GPGPU/Xeon Phi market maybe ~ $500M/year ... | Mark Roulo | 2013/11/20 10:35 AM |
Knights Landing CPU Speculation | Wes Felter | 2013/11/19 12:06 PM |
Knights Landing CPU Speculation | Michael S | 2013/11/19 12:49 PM |
Knights Landing CPU Speculation | Eric | 2013/11/18 12:17 PM |
Knights Landing CPU Speculation | Daniel | 2013/11/19 02:28 AM |
Knights Landing CPU Speculation | Eric | 2013/11/19 07:36 PM |
HPC guys score FLOPS non-obviously | Mark Roulo | 2013/11/20 10:43 AM |
3-TFlops-DGEMM | Michael S | 2013/11/20 10:59 AM |
3-TFlops-DGEMM | Mark Roulo | 2013/11/20 12:22 PM |
3-TFlops-DGEMM | Daniel | 2013/11/20 01:04 PM |
3-TFlops-DGEMM | Eric | 2013/11/21 01:28 AM |
3-TFlops-DGEMM | Michael S | 2013/11/21 05:48 AM |
3-TFlops-DGEMM | RecessionCone | 2013/11/21 11:13 AM |
3-TFlops-DGEMM | Michael S | 2013/11/21 02:34 PM |
3-TFlops-DGEMM | Eric | 2013/11/22 02:10 AM |
3-TFlops-DGEMM | Michael S | 2013/11/22 04:41 AM |
A (not very sensible) alternative: FMADD + FADD | Paul A. Clayton | 2013/11/22 08:19 AM |
3-TFlops-DGEMM | Sylvain Collange | 2013/11/24 02:37 AM |
3-TFlops-DGEMM | Michael S | 2013/11/24 06:06 AM |
3-TFlops-DGEMM | Sylvain Collange | 2013/11/24 09:28 AM |
HPC guys score FLOPS non-obviously | Patrick Chase | 2013/11/23 02:58 PM |
Knights Landing CPU Speculation | Paul Caheny | 2013/11/18 01:25 PM |
Knights Landing CPU Speculation | Konrad Schwarz | 2013/11/19 12:24 AM |
Knights Landing CPU Speculation | Amiba Gelos | 2013/11/19 07:36 PM |
Knights Landing CPU Speculation | David Kanter | 2013/11/20 09:52 AM |
Knights Landing CPU Speculation | Linus Torvalds | 2013/11/21 02:12 PM |
Knights Landing CPU Speculation | Amiba Gelos | 2013/11/21 05:14 PM |
Knights Landing CPU Speculation | Patrick Chase | 2013/11/23 03:33 PM |
Knights Landing CPU Speculation | Linus Torvalds | 2013/11/25 11:29 AM |
Knights Landing CPU Speculation | Linus Torvalds | 2013/11/25 12:05 PM |
Knights Landing CPU Speculation | Patrick Chase | 2013/11/25 12:22 PM |
Knights Landing CPU Speculation | Linus Torvalds | 2013/11/26 10:11 AM |
Knights Landing CPU Speculation | Eric | 2013/11/26 03:05 AM |
Knights Landing CPU Speculation | Eric | 2013/11/26 03:15 AM |
Knights Landing CPU Speculation | none | 2013/11/26 03:33 AM |
Knights Landing CPU Speculation | Eric | 2013/11/26 06:30 PM |
Knights Landing CPU Speculation | Eric | 2013/11/26 06:34 PM |
What is MCDRAM? | anon | 2013/11/26 08:58 PM |
What is MCDRAM? | none | 2013/11/27 01:00 AM |
What is MCDRAM? | Klimax | 2013/11/27 02:19 AM |
Knights Landing CPU Speculation | Klimax | 2013/11/26 11:06 PM |
Knights Landing CPU Speculation | Klimax | 2013/11/26 11:05 PM |
Knights Landing CPU Speculation | anon | 2013/11/26 05:53 AM |
Knights Landing CPU Speculation | none | 2013/11/26 06:20 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/26 08:06 AM |
Knights Landing CPU Speculation | none | 2013/11/26 09:18 AM |
Knights Landing CPU Speculation | Eric Bron | 2013/11/26 01:21 PM |
Knights Landing CPU Speculation | Eric Bron | 2013/11/26 01:27 PM |
Knights Landing CPU Speculation | none | 2013/11/26 02:26 PM |
Knights Landing CPU Speculation | anon | 2013/11/26 05:42 PM |
Knights Landing CPU Speculation | none | 2013/11/27 01:08 AM |
Knights Landing CPU Speculation | anon | 2013/11/27 01:50 AM |
Knights Landing CPU Speculation | none | 2013/11/27 01:58 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/27 01:25 AM |
Knights Landing CPU Speculation | anon | 2013/11/27 02:32 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/27 03:08 AM |
Knights Landing CPU Speculation | Chung Leong | 2013/11/27 01:28 AM |
Knights Landing CPU Speculation | Michael S | 2013/11/27 02:53 AM |
Knights Landing CPU Speculation | Chung Leong | 2013/11/27 01:03 PM |
BiG.LiTTLe for KNL? | Jeff K | 2013/11/22 06:17 AM |
BiG.LiTTLe for KNL? | Patrick Chase | 2013/11/23 02:54 PM |
BiG.LiTTLe for KNL? | Patrick Chase | 2013/11/23 03:01 PM |
Transactional memory | Patrick Chase | 2013/11/23 02:37 PM |
Transactional memory | Bhima | 2013/11/25 07:01 AM |
Transactional memory | Patrick Chase | 2013/11/25 11:52 AM |
Knights Landing CPU Speculation | Daniel | 2013/11/25 02:17 AM |
Knights Landing CPU Speculation | Klimax | 2013/11/25 03:12 AM |
Knights Landing CPU Speculation | none | 2013/11/25 04:05 AM |
Knights Landing CPU Speculation | Klimax | 2013/11/25 04:45 AM |
Knights Landing CPU Speculation | none | 2013/11/25 04:55 AM |
Knights Landing CPU Speculation | gmb | 2013/11/25 07:21 AM |