Broadwell in a Server SoC

In a nutshell, the Xeon D-1540 is two silicon dies in one highly integrated package. Eight 14 nm Broadwell cores, a shared L3-cache, a dual 10 gigabit MAC, a PCIe 3.0 root with 24 lanes find a home in the integrated SoC whereas in the same package we find four USB 3.0, four USB 2.0, six SATA3 controllers and a PCIe 2.0 root integrated in a PCH chip.

 

The Broadwell architecture brings small microarchitectural improvements - Intel currently claims about 5.5% higher IPC in integer processing. Other improvements include slightly lower VM exit/enter latencies, something that Intel has been improving with almost every recent generation (excluding Sandy Bridge). 

Of course, if you are in the server business, you care little about all the small IPC improvements. Let us focus on the large relevant improvements. The big improvements over the Xeon E3-1200 v3 are:

  1. Twice as many cores and threads (8/16 vs 4/8)
  2. 32 GB instead of 8 GB per DIMM supported and support for DDR4-2133
  3. Maximum memory capacity has quadrupled (128 GB vs 32 GB)
  4. 24 PCIe 3.0 lanes instead of 16 PCIe 3.0 lanes
  5. 12 MB L3 rather than 8 MB L3
  6. No separate C22x chipset necessary for SATA / USB
  7. Dual 10 Gbit Ethernet integrated ...

And last but not least, RAS (Reliability, Availability and Servicability) features which are more similar to the Xeon E5:

The only RAS features missing in the Xeon D are the expensive ones like memory mirroring. Those RAS features a very rarely used, and The Xeon D can not offer them as it does not have a second memory controller. 

Compared to the Atom C2000, the biggest improvement is the fact that the Broadwell core is vastly more advanced than the Silvermont core. That is not all: 

  1. Atom C2000 had no L3-cache, and are thus a lot slower in situation where the cores have to sync a lot (databases)
  2. No support for USB 3 (Xeon D: four USB 3 controllers)
  3. As far as we know Atom C2000 server boards were limited to two 1 Gbit PHYs (unless you add a separate 10 GBe controller)
  4. No support for PCIe 3.0, "only" 16 PCIe Gen2 lanes. 

There are more subtle differences of course such as using a crossbar rather than a ring, but those are beyond the scope of this review.  

The Xeon D SoC Meet the SuperServer 5028D-TN4T
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  • Kjella - Tuesday, June 23, 2015 - link

    Server on a chip? It's not intended for use with a display, it does all it's "supposed to" do for the hyperscale market without any display. Reply
  • close - Tuesday, June 23, 2015 - link

    "Intel was able to combine 8 of them together with dual 10 Gbit, 4 USB 3.0 controllers, 6 SATA 3 controller and quite a bit more".
    This ^^ makes it a SoC. Ok, a video output would be nice but that certainly doesn't disqualify it.
    Reply
  • ats - Tuesday, June 23, 2015 - link

    cause video isn't required or even wanted in this market segment. It is a SoC, which simply means system on a chip and doesn't have some ironclad definition. Hell, most "SoC" chips aren't really systems on a chip anyways and require significant supporting logic (this is true for just about any cell phone SoC on the market too). Reply
  • bill.rookard - Tuesday, June 23, 2015 - link

    Exactly, you would tend to use remote management over the network to admin this type of a unit. I have several rackmounted servers in my basement (I do some home-serving of websites over a business class connection) and while I do have them actually hooked up to a display, I can hardly remember the last time I looked at them as 99.9% of the time I SSH into everything for administration.

    About the only time you'd ever really use a display is if you were doing multiple VMs of assorted types. Beyond that, it's wattage wasted.
    Reply
  • ats - Tuesday, June 23, 2015 - link

    Yeah honestly, having several SM boards with their ILM system, the only time I'd ever hook up a display is if the network was down. The SM ILM will fully proxy pretty much anything you want and give you a 1200p display that works for just about anything. And you can remotely hook up CDs, DVDs, BRs, USB, etc through it along with the stand console and keyboard/mouse functions. Its a very nice solution. Reply
  • nightbringer57 - Tuesday, June 23, 2015 - link

    Basically, you don't need video output.
    Even if you do, mainboard manufacturers usually include a third-party chip with dedicated functions that, along other things, provide a VGA port usable for a server use.
    In this case, the AST2400 chip offers some basic GPU functions with a VGA port along with many remote control-related stuff.
    Adding all those functions to the Intel SoC would be awfully expensive. The chip only requires a simple PCIe x1 connection from the SoC, but provides hundreds of additional pins. Not only would those functions probably be hard to implement on a relatively recent 14nm process, but it would require at least 300 new pins on the SoC to add all the 3rd party chip's functions on it, which is almost impossible to do.
    Reply
  • Th-z - Tuesday, June 23, 2015 - link

    There doesn't seem to have a concrete definition for the term SoC, but it's ridiculous now with the term SoC bandwagon. Everything seems to be called "SoC" these days as long as a chip has more than one functions integrated. One of examples is people even called current console's integrated CPU and GPU chip as SoC, which doesn't even have networking and other peripheral units in it. When a system has so many "SoCs" inside, the term really has lost its meaning and significance. Reply
  • redzo - Tuesday, June 23, 2015 - link

    I'm thinking this is a bad name for a product like this. It reminds of the infamous Celeron D and Pentium D line. Reply
  • nandnandnand - Tuesday, June 23, 2015 - link

    Anyone who can figure out Xeon D exists can probably tell the difference Reply
  • wussupi83 - Tuesday, June 23, 2015 - link

    I agree with redzo, I think anyone who can figure out a 'Xeon D' exists AND remembers that Pentium & Celeron D's existed would initially assume this is a budget Xeon - which it's clearly not. E4 sounds pretty logical. But sure lets just put D... Reply

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