7 ms·

Intel's 72-Core “Knight's Landing” Xeon Phi Chip Cleared for Takeoff

84 points by taspeotis 11y ago

hendzen 11y ago
The real question is when they will release a socketed version. The disadvantages of the PCI-E form factor are somewhat mitigated by the on-board memory, but it would still be nicer to not have to program against them as an accelerator card. EDIT: Looks like this is in the works already [0]. [0] - http://www.nextplatform.com/2015/03/25/more-knights-landing-xeon-phi-secrets-unveiled/ http://www.nextplatform.com/2015/03/25/more-knights-landing-...
- deleted 11y ago
  [deleted]
- rbanffy 11y ago
  I'd love to see these parts on the desks of developers. I can't imagine there are only 4 things my computer can be doing right now. And even if there aren't, it's about 16 times fewer context switches to do.
jd3 11y ago
nice. I remember reading about this (what feels like) ages ago at this point. Patiently waiting to see if Terry Davis shows up. reference:[0] [0]: https://usesthis.com/interviews/terry.davis/ https://usesthis.com/interviews/terry.davis/
chubot 11y ago
Hm I thought Xeon Phi was sort of a failed launch? I remember the previous version being heavily discounted at one point, and it didn't seem like they were releasing new versions very quickly. What are people using the Xeon Phi for? nVidia seems to be making a killing off machine learning applications. The entire GTC 2015 was about deep learning. I assume that Xeon Phi is not nearly as effective for machine learning (?).
- wyldfire 11y ago
  > sort of a failed launch Yeah. But I think it's good for Intel to follow through here instead of abandoning it like they did Larrabee. Intel has some real design talent, so it would be great if they can get their software team and hardware team to work on a solution that competes well with GPUs. It doesn't help Phi that Intel's OCL support isn't quite there yet, IMO. If they could just put their weight behind OCL and add their own extensions to support the cases where their accelerator design is different from GPUs, it would be attractive to HPC types to port their software to support it, IMO. > What are people using the Xeon Phi for? I don't know but I suspect it will shine for CPU-bound code that folks don't want to waste time porting x86 executables to a new language/framework. Memory-bound stuff will probably not see an advantage over GPUs. I don't think they'll attract enough attention to TBB/Cilk or whatever they're promoting alongside Phi.
- jandrewrogers 11y ago
  Xeon Phi is somewhat misunderstood, and its early incarnations have not helped that. The most important point to understand is that it is neither a CPU or GPU architecture. Code designed for either of those architectures will be very suboptimal even if it does run adequately. The Xeon Phi is a modern reincarnation of a barrel processor. It understands x86-64 opcodes but your data structures and algorithms need to be designed quite differently than vanilla CPU code if you want to optimize throughput. No one is doing that though. In principle, if your code is correctly designed for the architecture, the Xeon Phi should significantly outperform both CPUs and GPUs for a wide range of use cases. The strength of these architectures is that their throughput is relatively insensitive to both latency and lack of trivial parallelism, which are the major bottlenecks to a lot of modern software performance. It is why Intel resurrected this style of computing architecture. Basically, very few people know how to design software for these architectures even though it is pretty easy (much easier than GPU code). I have experience designing software for exotic architectures like this, I know what they are capable of in terms of throughput, but have never worked with a Xeon Phi. Nonetheless, the silicon specs suggest that someone that actually knows what they are doing should be able to significantly outperform e.g. GPUs for things like machine learning. Right now, it is basically being wasted because most developers treat them like weird CPUs. I'd love to play with one of the new Xeon Phi processors to characterize its true performance but I am unlikely to see one. But I would not dismiss their performance; it is an extremely efficient kind of architecture for a surprisingly wide range of workloads if used well.
modeless 11y ago
NVIDIA Titan X today: 336 GB/s, 7 teraflops Intel Xeon Phi next year: 400 GB/s, 6 teraflops NVIDIA Pascal next year: 1 TB/s, >10? teraflops NVIDIA still wins for my applications. Intel is aiming too low.
- wyldfire 11y ago
  Yeah, Intel's behind the curve for sure. But what if they had a soup-to-nuts open ecosystem? IMO that can be a real winner for simple, convenient deployment of a total solution. It doesn't make up for being a generation+ behind, but I expect they'll catch up over time.
  - modeless 11y ago
    I'm not sure Intel will catch up. Underestimating the power and importance of graphics hardware seems to be a chronic problem that they have. It's a shame NVIDIA's Project Denver custom CPU didn't seem to work out very well. I was really hoping they'd be able to produce a CPU worthy of pairing with their top-end GPUs, to make an x86-free workstation and lessen their dependence on Intel. Wouldn't that be something?
- rdtsc 11y ago
  Why do you think they still do it? It would seem they have enough people for someone to check NVIDIA's numbers. Are they offering something closer to general purpose CPUs, something that could schedule OS threads to run on it?
  - ScottBurson 11y ago
    According to the article hendzen linked to, the Phi processors are absolutely general purpose CPUs -- they can be the main CPU on the board and can boot and run stock OSes. This is much more powerful than a GPU, which is fundamentally SIMD -- it can hit TFLOPS speeds running hundreds of threads doing different things. While not everyone will need this power, I suspect it will open up entire new classes of applications.
rtl49 11y ago
On a related subject, can someone shed some light on the reasons and maybe the legal justification for export controls for these processors? I recall reading an article a few months ago about limitations imposed on exports to China of Xeon processors. Are these such a competitive advantage?
- SXX 11y ago
  It's wasn't ban just for Intel Xeon, but Nvidia and AMD as well. So it is competitive advantage because there are no alternatives. It's obvious that such restrictions won't affect China's access to actual hardware, but prevent their cooperation with CPU/GPU vendors.
- deleted 11y ago
  [deleted]
curiousAl 11y ago
How many years therapy does this come with for the person who has to push down the motherboard lever?
- sdrothrock 11y ago
  None, since it's a PCI-E card, not a processor. (I'm assuming you were referring to the possibility of bending pins by trying to mount a processor incorrectly? Might be way off.)
  - simcop2387 11y ago
    He might have been referring to the non-pci-e version that's in the works, as hendzen pointed out: http://www.nextplatform.com/2015/03/25/more-knights-landing-xeon-phi-secrets-unveiled/ http://www.nextplatform.com/2015/03/25/more-knights-landing-... It looks really beefy.
dman 11y ago
Are there any publicly accessible clusters/clouds with these?
dkbrk 11y ago
I was wondering how radically this architecture differs from more conventional x86 cores, and found this: "An Overview of Programming for Intel Xeon processors and Intel Xeon Phi coprocessors (2012)" [0]. This paper refers to a slightly older architecture - "Knight's Corner", but it should be roughly the same. Essentially, it has a large number of x86 cores with 4 in-order threads per core. Each core has a 512 KB L2 cache and the entire coprocessor is cache-coherent through a high-speed ring bus. There is also some quantity of GDDR5 (up to 8GB) on said ring bus. The great advantage over Xeon is its scaling to very high levels of parallelism: though threads on the same core will benefit from data locality, the architecture scales uniformly with more cores unlike a NUMA multi-socket setup. There's more information about the sorts of optimisations required to get good performance in the paper, but they're much the same sort of things as for Xeon. Also, according to the paper, any algorithm well suited for a GPU is well suited to the Phi architecture, though the Phi architecture is far more general-purpose in its applications. [0] - https://software.intel.com/sites/default/files/article/330164/an-overview-of-programming-for-intel-xeon-processors-and-intel-xeon-phi-coprocessors_1.pdf https://software.intel.com/sites/default/files/article/33016...
- knweiss 11y ago
  The Knights Landing (KNL) memory hierarchy is different from Knights Corner because it now features MCDRAM (HBM) - even with three different modes [0]. [0] - http://www.anandtech.com/show/9794/a-few-notes-on-intels-knights-landing-and-mcdram-modes-from-sc15 http://www.anandtech.com/show/9794/a-few-notes-on-intels-kni...
- yvdriess 11y ago
  > I was wondering how radically this architecture differs from more conventional x86 cores The big difference besides memory and organisation is that the KNL cores are beefed-up Silvermont cores (the new Atom), which is an out of order core and pretty much what you would expect of a modern x86 architecture. The Knight's Corner cores were custom cores, somewhere between barrel and vector processors. The Knight's Landing should be even more general-purpose than the old Xeon Phi's and easier to program for.
afsina 11y ago
AMD will probably have a 32 core CPU by the time (If they are not bankrupt). It would offer a better performance since Xeon Phi CPUs are probably weaker. http://wccftech.com/amd-exascale-heterogeneous-processor-ehp-apu-32-zen-cores-hbm2/ http://wccftech.com/amd-exascale-heterogeneous-processor-ehp...
- cma 11y ago
  32 core, or "32 core": http://www.pcworld.com/article/3003113/components-processors/lawsuit-alleges-amds-bulldozer-cpus-arent-really-8-core-processors.html http://www.pcworld.com/article/3003113/components-processors...
  - afsina 11y ago
    Cores are real Zen cores with dedicated FPU units. This has nothing to do with bulldozer.
  - greggyb 11y ago
    AMD's new Zen architecture implements SMT, similar to Intel's hyperthreading. The contention about core count on the Bulldozer architecture seems spurious to me. At the time Bulldozer was being developed, multi-core systems were just being introduced to the consumer market. It was unclear what sort of architecture would be most performant. AMD made a (bad only in hindsight) bet that Bulldozer would be a viable architecture for general purpose compute loads. It turns out that combining 1 FPU with two integer pipelines is not as effective as an SMT architecture. At the time Bulldozer was developed and released, what exactly constituted a core was still not precisely defined. It turns out that Intel's SMT architecture is much more effective, and thanks to market- and mind-share, people associate the definition of a core with Intel's specific implementation. AMD's new development is on an SMT architecture known as Zen. Like all AMD news and marketing, it sounds exciting. Hopefully they execute well and it actually turns out to be exciting.
- mtanski 11y ago
  However these still have higher bandwidth memory for streaming data in/out of processing. Increasing core count without increasing memory throughput only works for some types of problems (with high locality of data).
InfiniteEntropy 11y ago
Finally, the hardware to run Crysis on high exists.
mrb 11y ago
It took Intel 10 years, starting with Larrabee in 2006, to finally produce a MIC architecture that reaches the same level of performance as high-end GPUs: AMD's, Nvidia's, and Intel's top chips now all hit 6-8 single-precision teraflops per chip. This will hopefully bring some competition to the GPU compute market which is currently owned by Nvidia. The two main reasons Knights Landing is so competitive compared to the previous-generation Knights Corner is that (1) it doubled the raw compute performance per core thanks to its two 512-bit VPUs (vector processing units) per core compared to only 1 VPU per core for Knights Corner, and (2) it upped the number of cores from 61 to 72 while maintaining and even slightly increasing the clock frequency from 1.25 GHz to 1.3 GHz. All this was possible because Knights Landing is manufactured in 14nm while Knights Corner was 22nm, so its logic gates are 2-2.5x denser. Meanwhile all AMD and Nvidia discrete GPUs are still stuck at 28nm. The only reason GPUs still perform comparably to Knights Landing is that their execution units are simpler and smaller than Intel MIC cores.

84 points by taspeotis 11y ago

The real question is when they will release a socketed version. The disadvantages of the PCI-E form factor are somewhat mitigated by the on-board memory, but it would still be nicer to not have to program against them as an accelerator card. EDIT: Looks like this is in the works already [0]. [0] - http://www.nextplatform.com/2015/03/25/more-knights-landing-xeon-phi-secrets-unveiled/ http://www.nextplatform.com/2015/03/25/more-knights-landing-...

deleted 11y ago
[deleted]
rbanffy 11y ago
I'd love to see these parts on the desks of developers. I can't imagine there are only 4 things my computer can be doing right now. And even if there aren't, it's about 16 times fewer context switches to do.

jd3 11y ago

nice. I remember reading about this (what feels like) ages ago at this point. Patiently waiting to see if Terry Davis shows up. reference:[0] [0]: https://usesthis.com/interviews/terry.davis/ https://usesthis.com/interviews/terry.davis/

chubot 11y ago

Hm I thought Xeon Phi was sort of a failed launch? I remember the previous version being heavily discounted at one point, and it didn't seem like they were releasing new versions very quickly. What are people using the Xeon Phi for? nVidia seems to be making a killing off machine learning applications. The entire GTC 2015 was about deep learning. I assume that Xeon Phi is not nearly as effective for machine learning (?).

wyldfire 11y ago
> sort of a failed launch Yeah. But I think it's good for Intel to follow through here instead of abandoning it like they did Larrabee. Intel has some real design talent, so it would be great if they can get their software team and hardware team to work on a solution that competes well with GPUs. It doesn't help Phi that Intel's OCL support isn't quite there yet, IMO. If they could just put their weight behind OCL and add their own extensions to support the cases where their accelerator design is different from GPUs, it would be attractive to HPC types to port their software to support it, IMO. > What are people using the Xeon Phi for? I don't know but I suspect it will shine for CPU-bound code that folks don't want to waste time porting x86 executables to a new language/framework. Memory-bound stuff will probably not see an advantage over GPUs. I don't think they'll attract enough attention to TBB/Cilk or whatever they're promoting alongside Phi.
jandrewrogers 11y ago
Xeon Phi is somewhat misunderstood, and its early incarnations have not helped that. The most important point to understand is that it is neither a CPU or GPU architecture. Code designed for either of those architectures will be very suboptimal even if it does run adequately. The Xeon Phi is a modern reincarnation of a barrel processor. It understands x86-64 opcodes but your data structures and algorithms need to be designed quite differently than vanilla CPU code if you want to optimize throughput. No one is doing that though. In principle, if your code is correctly designed for the architecture, the Xeon Phi should significantly outperform both CPUs and GPUs for a wide range of use cases. The strength of these architectures is that their throughput is relatively insensitive to both latency and lack of trivial parallelism, which are the major bottlenecks to a lot of modern software performance. It is why Intel resurrected this style of computing architecture. Basically, very few people know how to design software for these architectures even though it is pretty easy (much easier than GPU code). I have experience designing software for exotic architectures like this, I know what they are capable of in terms of throughput, but have never worked with a Xeon Phi. Nonetheless, the silicon specs suggest that someone that actually knows what they are doing should be able to significantly outperform e.g. GPUs for things like machine learning. Right now, it is basically being wasted because most developers treat them like weird CPUs. I'd love to play with one of the new Xeon Phi processors to characterize its true performance but I am unlikely to see one. But I would not dismiss their performance; it is an extremely efficient kind of architecture for a surprisingly wide range of workloads if used well.

modeless 11y ago

NVIDIA Titan X today: 336 GB/s, 7 teraflops Intel Xeon Phi next year: 400 GB/s, 6 teraflops NVIDIA Pascal next year: 1 TB/s, >10? teraflops NVIDIA still wins for my applications. Intel is aiming too low.

wyldfire 11y ago
Yeah, Intel's behind the curve for sure. But what if they had a soup-to-nuts open ecosystem? IMO that can be a real winner for simple, convenient deployment of a total solution. It doesn't make up for being a generation+ behind, but I expect they'll catch up over time.
- modeless 11y ago
  I'm not sure Intel will catch up. Underestimating the power and importance of graphics hardware seems to be a chronic problem that they have. It's a shame NVIDIA's Project Denver custom CPU didn't seem to work out very well. I was really hoping they'd be able to produce a CPU worthy of pairing with their top-end GPUs, to make an x86-free workstation and lessen their dependence on Intel. Wouldn't that be something?
rdtsc 11y ago
Why do you think they still do it? It would seem they have enough people for someone to check NVIDIA's numbers. Are they offering something closer to general purpose CPUs, something that could schedule OS threads to run on it?
- ScottBurson 11y ago
  According to the article hendzen linked to, the Phi processors are absolutely general purpose CPUs -- they can be the main CPU on the board and can boot and run stock OSes. This is much more powerful than a GPU, which is fundamentally SIMD -- it can hit TFLOPS speeds running hundreds of threads doing different things. While not everyone will need this power, I suspect it will open up entire new classes of applications.

rtl49 11y ago

On a related subject, can someone shed some light on the reasons and maybe the legal justification for export controls for these processors? I recall reading an article a few months ago about limitations imposed on exports to China of Xeon processors. Are these such a competitive advantage?

SXX 11y ago
It's wasn't ban just for Intel Xeon, but Nvidia and AMD as well. So it is competitive advantage because there are no alternatives. It's obvious that such restrictions won't affect China's access to actual hardware, but prevent their cooperation with CPU/GPU vendors.
deleted 11y ago
[deleted]

curiousAl 11y ago

How many years therapy does this come with for the person who has to push down the motherboard lever?

sdrothrock 11y ago
None, since it's a PCI-E card, not a processor. (I'm assuming you were referring to the possibility of bending pins by trying to mount a processor incorrectly? Might be way off.)
- simcop2387 11y ago
  He might have been referring to the non-pci-e version that's in the works, as hendzen pointed out: http://www.nextplatform.com/2015/03/25/more-knights-landing-xeon-phi-secrets-unveiled/ http://www.nextplatform.com/2015/03/25/more-knights-landing-... It looks really beefy.

dman 11y ago

Are there any publicly accessible clusters/clouds with these?

dkbrk 11y ago

I was wondering how radically this architecture differs from more conventional x86 cores, and found this: "An Overview of Programming for Intel Xeon processors and Intel Xeon Phi coprocessors (2012)" [0]. This paper refers to a slightly older architecture - "Knight's Corner", but it should be roughly the same. Essentially, it has a large number of x86 cores with 4 in-order threads per core. Each core has a 512 KB L2 cache and the entire coprocessor is cache-coherent through a high-speed ring bus. There is also some quantity of GDDR5 (up to 8GB) on said ring bus. The great advantage over Xeon is its scaling to very high levels of parallelism: though threads on the same core will benefit from data locality, the architecture scales uniformly with more cores unlike a NUMA multi-socket setup. There's more information about the sorts of optimisations required to get good performance in the paper, but they're much the same sort of things as for Xeon. Also, according to the paper, any algorithm well suited for a GPU is well suited to the Phi architecture, though the Phi architecture is far more general-purpose in its applications. [0] - https://software.intel.com/sites/default/files/article/330164/an-overview-of-programming-for-intel-xeon-processors-and-intel-xeon-phi-coprocessors_1.pdf https://software.intel.com/sites/default/files/article/33016...

knweiss 11y ago
The Knights Landing (KNL) memory hierarchy is different from Knights Corner because it now features MCDRAM (HBM) - even with three different modes [0]. [0] - http://www.anandtech.com/show/9794/a-few-notes-on-intels-knights-landing-and-mcdram-modes-from-sc15 http://www.anandtech.com/show/9794/a-few-notes-on-intels-kni...
yvdriess 11y ago
> I was wondering how radically this architecture differs from more conventional x86 cores The big difference besides memory and organisation is that the KNL cores are beefed-up Silvermont cores (the new Atom), which is an out of order core and pretty much what you would expect of a modern x86 architecture. The Knight's Corner cores were custom cores, somewhere between barrel and vector processors. The Knight's Landing should be even more general-purpose than the old Xeon Phi's and easier to program for.

afsina 11y ago

AMD will probably have a 32 core CPU by the time (If they are not bankrupt). It would offer a better performance since Xeon Phi CPUs are probably weaker. http://wccftech.com/amd-exascale-heterogeneous-processor-ehp-apu-32-zen-cores-hbm2/ http://wccftech.com/amd-exascale-heterogeneous-processor-ehp...

cma 11y ago
32 core, or "32 core": http://www.pcworld.com/article/3003113/components-processors/lawsuit-alleges-amds-bulldozer-cpus-arent-really-8-core-processors.html http://www.pcworld.com/article/3003113/components-processors...
- afsina 11y ago
  Cores are real Zen cores with dedicated FPU units. This has nothing to do with bulldozer.
- greggyb 11y ago
  AMD's new Zen architecture implements SMT, similar to Intel's hyperthreading. The contention about core count on the Bulldozer architecture seems spurious to me. At the time Bulldozer was being developed, multi-core systems were just being introduced to the consumer market. It was unclear what sort of architecture would be most performant. AMD made a (bad only in hindsight) bet that Bulldozer would be a viable architecture for general purpose compute loads. It turns out that combining 1 FPU with two integer pipelines is not as effective as an SMT architecture. At the time Bulldozer was developed and released, what exactly constituted a core was still not precisely defined. It turns out that Intel's SMT architecture is much more effective, and thanks to market- and mind-share, people associate the definition of a core with Intel's specific implementation. AMD's new development is on an SMT architecture known as Zen. Like all AMD news and marketing, it sounds exciting. Hopefully they execute well and it actually turns out to be exciting.
mtanski 11y ago
However these still have higher bandwidth memory for streaming data in/out of processing. Increasing core count without increasing memory throughput only works for some types of problems (with high locality of data).

InfiniteEntropy 11y ago

Finally, the hardware to run Crysis on high exists.

mrb 11y ago

It took Intel 10 years, starting with Larrabee in 2006, to finally produce a MIC architecture that reaches the same level of performance as high-end GPUs: AMD's, Nvidia's, and Intel's top chips now all hit 6-8 single-precision teraflops per chip. This will hopefully bring some competition to the GPU compute market which is currently owned by Nvidia. The two main reasons Knights Landing is so competitive compared to the previous-generation Knights Corner is that (1) it doubled the raw compute performance per core thanks to its two 512-bit VPUs (vector processing units) per core compared to only 1 VPU per core for Knights Corner, and (2) it upped the number of cores from 61 to 72 while maintaining and even slightly increasing the clock frequency from 1.25 GHz to 1.3 GHz. All this was possible because Knights Landing is manufactured in 14nm while Knights Corner was 22nm, so its logic gates are 2-2.5x denser. Meanwhile all AMD and Nvidia discrete GPUs are still stuck at 28nm. The only reason GPUs still perform comparably to Knights Landing is that their execution units are simpler and smaller than Intel MIC cores.