Article: Knights Landing CPU Speculation
By: Patrick Chase (patrickjchase.delete@this.hp.com), November 23, 2013 3:33 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 (torvalds.delete@this.linux-foundation.org) on November 21, 2013 3:12 pm wrote:
> Amiba Gelos (b98202036.delete@this.ntu.edu.tw) 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.
Linus Torvalds (torvalds.delete@this.linux-foundation.org) on November 21, 2013 3:12 pm wrote:
> Amiba Gelos (b98202036.delete@this.ntu.edu.tw) 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.
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 |