didn't this whole processor line get cancelled?
Knight’s Landing: Atom with AVX-512
11–20 of 37 posts
Re: Knight’s Landing: Atom with AVX-512
#12Great in-depth article. One especially interesting data point relevant to ongoing discussions about AVX-512 area cost: 40% of 2.93 mm2 per core is AVX-512, so 1.14 mm2. This is a large fraction, but as the article says the core is basically a minimum wrapper around the vector unit, with rather weak L1i/branch predictor/store buffers. Let's put that in the context of modern chips. 14nm density was 44.67 MTr/mm2 so tha…
Good analysis. It's also worth pointing out that this is for 2x 512 bit FMA, which is more than client Ice/Tiger/Rocket lake or Zen4 have.
Personally, I bought HEDT (Skylake-X and Cascadelake) because I wanted 2x 512 bit AVX512. Glad it's cheap in terms of area, and I'm hoping we'll get more options with great vector performance in the future.
Re: Knight’s Landing: Atom with AVX-512
#13Finally! One of the excellent excellent Chips & Cheese coverages of a really weird chip! Nice! > Intel spends nearly 40% of the core’s die area to implement wide AVX-512 execution, so Knight’s Landing gets some incredibly high throughput for a low power architecture. In fact, it almost feels like a small OoO core built around feeding giant vector units Well said! There's some interesting details here. I love how the…
Reading it, it seems very similar to the Playstation 3 Cell, with its fate mirroring it very much. A highly specialized processor that has very high computational throughput for specialized operations, but a quite limited scalar unit. In both cases you really have to write software specifically for it to get it to perform with any reasonable speed. If you do that, you get great value, but any existing code will need…
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Re: Knight’s Landing: Atom with AVX-512
#14Not denying that there are use cases...but my first reaction to "Atom with AVX-512" is "Fiat 500 with a 5th Wheel".
Re: Knight’s Landing: Atom with AVX-512
#15The Xeon Phi coprocessor pci-e cards with similar CPU can be had on ebay for like $60 these days. Sadly I haven't seen any good writeups on setting up an environment to run such cards in a homebuilt system. I think it would be neat to build a little mini-supercomputer with 8 of them stacked in one of those mining motherboards with 8 pci-e slots. But I'd have no idea where to start with the toolchain needed to compile an run code across them.
Re: Knight’s Landing: Atom with AVX-512
#16Tom Forsyth gave a talk at handmade seattle 2019 titled "SMACNI to AVX512 the life cycle of an instruction set"
https://guide.handmade-seattle.com/c/2019/talks/lifecycle-of...
Re: Knight’s Landing: Atom with AVX-512
#17The Xeon Phi coprocessor pci-e cards with similar CPU can be had on ebay for like $60 these days. Sadly I haven't seen any good writeups on setting up an environment to run such cards in a homebuilt system. I think it would be neat to build a little mini-supercomputer with 8 of them stacked in one of those mining motherboards with 8 pci-e slots. But I'd have no idea where to start with the toolchain needed to compile…
The original cards couldn't be thermally throttle, safely. Whenever the union guys came to our floor they were required to wear PPE (helmet, goggles, earplugs, earmuffs, and a vest). It was as loud as a high powered low quality vacuum cleaner. Staying within 5' of the towers, when running, without ear protection was an OSHA violation.
Re: Knight’s Landing: Atom with AVX-512
#18The Xeon Phi coprocessor pci-e cards with similar CPU can be had on ebay for like $60 these days. Sadly I haven't seen any good writeups on setting up an environment to run such cards in a homebuilt system. I think it would be neat to build a little mini-supercomputer with 8 of them stacked in one of those mining motherboards with 8 pci-e slots. But I'd have no idea where to start with the toolchain needed to compile…
I remember playing with them at the local supercomputer facility. I thought it was so funny that you were expected to ssh into a pcie device.
Re: Knight’s Landing: Atom with AVX-512
#19The Xeon Phi coprocessor pci-e cards with similar CPU can be had on ebay for like $60 these days. Sadly I haven't seen any good writeups on setting up an environment to run such cards in a homebuilt system. I think it would be neat to build a little mini-supercomputer with 8 of them stacked in one of those mining motherboards with 8 pci-e slots. But I'd have no idea where to start with the toolchain needed to compile…
The only Xeon Phi products to be available in PCIe form are the first-gen KNC cards. These are not Atom-based, they do not share the x86_64 ABI, and the only effective toolchain for them is older versions of the proprietary Intel compiler.
While they were quirky at the time (and I got some neat simulations out of them), they were a massive pain in the ass in every other way:
- Requires a motherboard that supports large PCIe BAR addressing, much more common now, not at release time (and good luck getting this working with multiple Xeon Phi coprocessors on a non-server motherboard) - You likely need enough host memory to cover each of the cards (so 8GB * number of cards) - You'll need to patch the Intel MPSS kernel driver to work with newer kernels - You'll need to patch the Intel MPSS tools to work on anything that isn't ~2015 RHEL - You'll want to buy the water cooling kit that alphacool made for them, it's the only way to keep temperatures and noise to a reasonable level
Solve all of those, and you get a (fairly cheap) coprocessor reasonably good at parallel yet branchy tasks. It's much easier to use the second generation of KNL (or third-generation KNM) which share the standard X86_64 ABI and can boot a modern Linux distro and you can use a normal toolchain).
Re: Knight’s Landing: Atom with AVX-512
#20didn't this whole processor line get cancelled?
Yes, they were canceled several years ago.