"It looks the same on the powerpoint slide, but they are very different". The place is Austin, where an AMD engineer is commenting on the slides describing the Zen and Skylake schematics. In Portland, the Intel representatives could not agree more: "the implementation matters and is completely different". "We have to educate our customers that they can not simply compare AMD's 32 core with our 28 cores".

This morning kicks off a very interesting time in the world of server-grade CPUs. Officially launching today is Intel's latest generation of Xeon processors, based on the "Skylake-SP" architecture. The heart of Intel's new Xeon Scalable Processor family, the "Purley" 100-series processors incorporate all of Intel's latest CPU and network fabric technology, not to mention a very large number of cores.

Meanwhile, a couple of weeks back AMD soft-launched their new EPYC 7000 series processors. Based on the company's Zen architecture and scaled up to server-grade I/O and core counts, EPYC represents an epic achievement for AMD, once again putting them into the running for competitive, high performance server CPUs after nearly half a decade gone. EPYC processors have begun shipping, and just in time for today's Xeon launch, we also have EPYC hardware in the lab to test.

Today's launch is a situation that neither company has been in for quite a while. Intel hasn't had serious competition in years, and AMD has't been able to compete. As a result, both companies are taking the other's actions very seriously.

In fact we could go on for much longer than our quip above in describing the rising tension at the headquarters of AMD and Intel. For the first time in 6 years (!), a credible alternative is available for the newly launched Xeon. Indeed, the new Xeon "Skylake-SP" is launching today, and the yardstick for it is not the previous Xeon (E5 version 4), but rather AMD's spanking new EPYC server CPU. Both CPUs are without a doubt very different: micro architecture, ISA extentions, memory subsystem, node topology... you name it. The end result is that once again we have the thrilling task of finding out how the processors compare and which applications their various trade-offs make sense.

The only similarity is that both server packages are huge. Above you see the two new Xeon packages –with and without an Omni-Path connector – both of which are as big as a keycard. And below you can see how one EPYC CPU fills the hand of AMD's CEO Dr. Lisa Su. 

Both are 64 bit x86 CPUs, but that is where the similarities end. For those of you who have been reading Ian's articles closely, this is no surprise. The consumer-focused Skylake-X is the little brother of the newly launched Xeon "Purley", both of which are cut from the same cloth that is the Skylake-SP family. In a nutshell, the Skylake-SP family introduces the following new features: 

  1. AVX-512 (Many different variants of the ISA extension are available)
  2. A 1 MB (instead of a 256 KB) L2-cache with a non-inclusive L3
  3. A mesh topology to connected the cores and L3-cache chunks together

Meanwhile AMD's latest EPYC Server CPU was launched a few weeks ago:

On the package are four silicon dies, each one containing the same 8-core silicon we saw in the AMD Ryzen processors. Each silicon die has two core complexes, each of four cores, and supports two memory channels, giving a total maximum of 32 cores and 8 memory channels on an EPYC processor. The dies are connected by AMD’s newest interconnect, the Infinity Fabric...

In the next pages, we will be discussing the impact of these architectural choices on server software. 

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  • Shankar1962 - Wednesday, July 12, 2017 - link

    AMD is fooling everyone one by showing more cores, pci lanes, security etc
    Can someone explain me why GOOGLE ATT AWS ALIBABA etc upgraded to sky lake when AMD IS SUPERIOR FOR HALF THE PRICE?
  • Shankar1962 - Wednesday, July 12, 2017 - link

    Sorry its Baidu
    Pretty sure Alibaba will upgrade

  • PixyMisa - Thursday, July 13, 2017 - link

    Lots of reasons.

    1. Epyc is brand new. You can bet that every major server customer has it in testing, but it could easily be a year before they're ready to deploy.
    2. Functions like ESXi hot migration may not be supported on Epyc yet, and certainly not between Epyc and Intel.
    3. Those companies don't pay the same prices we do. Amazon have customised CPUs for AWS - not a different die, but a particular spec that isn't on Intel's product list.

    There's no trick here. This is what AMD did before, back in 2006.
  • blublub - Tuesday, July 11, 2017 - link

    I kinda miss Infinity Fabric on my Haswell CPU and it seems to only have on die - so why is that missing on Haswell wehen Ryzen is an exact copy?
  • blublub - Tuesday, July 11, 2017 - link

    argh that post did get lost.
  • zappor - Tuesday, July 11, 2017 - link

    4.4.0 kernel?! That's not good for single-die Zen and must be even worse for Epyc!

    AMD's Ryzen Will Really Like A Newer Linux Kernel:

    Kernel 4.10 gives Linux support for AMD Ryzen multithreading:
  • JohanAnandtech - Friday, July 21, 2017 - link

    We will update to a more updated kernel once the hardware update for 16.04 LTS is available. Should be August according to Ubuntu
  • kwalker - Tuesday, July 11, 2017 - link

    You mention an OpenFOAM benchmark when talking about the new mesh topology but it wasn't included in the article. Any way you could post that? We are trying to evaluate EPYC vs Skylake for CFD applications.
  • JohanAnandtech - Friday, July 21, 2017 - link

    Any suggestion on a good OpenFoam benchmark that is available? Our realworld example is not compatible with the latest OpenFoam versions. Just send me an e-mail, if you can assist.
  • Lolimaster - Tuesday, July 11, 2017 - link

    AMD's lego design where basically every CCX can be used in whatever config they want be either consumer/HEDT or server is superior in the multicore era.

    Cheaper to produce, cheaper to sell, huge profits.

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