The Intel Xeon D Review: Performance Per Watt Server SoC Champion?
by Johan De Gelas on June 23, 2015 8:35 AM EST- Posted in
- CPUs
- Intel
- Xeon-D
- Broadwell-DE
Memory Subsystem: Bandwidth
As more memory channels complicate motherboard design and can be a problem for dense servers, the Xeon-D, Xeon E3 and Atom C2000 only have two memory channels. This makes quad channel operation a good way to differentiate up to the Xeon E5. The Xeon E3 and Atom are limited to DDR3-1600 as per JEDEC specifications, whereas the Xeon D should be able to command more bandwidth due to the use of DDR4-2133 DIMMs.
We measured the memory bandwidth in Linux. The binary was compiled with the Open64 compiler 5.0 (Opencc). It is a multi-threaded, OpenMP based, 64-bit binary. The following compiler switches were used:
-Ofast -mp -ipa
To keep things simple, we only report the Triad sub-benchmark of our OpenMP enabled Stream benchmark.
Using DIMMs with a 33% higher clock, the Xeon D gets a 25-38% boost in bandwidth compared to the Xeon E3. Basically, every percent increase in clock speed is translated in higher bandwidth. The Xeon E5 has almost twice as much bandwidth for only 50% more cores and should as result do better in some bandwidth intensive applications (mostly HPC).
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extide - Tuesday, June 23, 2015 - link
That's ECC Registered, -- not sure if it will take that, but probably, although you dont need registered, or ECC.nils_ - Wednesday, June 24, 2015 - link
If you want transcoding, you might want to look at the Xeon E3 v4 series instead, which come with Iris Pro graphics. Should be a lot more efficient.bernstein - Thursday, June 25, 2015 - link
for using ECC UDIMMs, a cheaper option would be an i3 in a xeon e3 board.psurge - Tuesday, June 23, 2015 - link
Has Intel discussed their Xeon-D roadmap at all? I'm wondering in particular if 2x25GbE is coming, whether we can expect a SOC with higher clock-speed or more cores (at a higher TDP), and what the timeframe is for Skylake based cores.nils_ - Tuesday, June 23, 2015 - link
Is 25GbE even a standard? I've heard about 40GbE and even 56GbE (matching infiniband), but not 25.psurge - Tuesday, June 23, 2015 - link
It's supposed be a more cost effective speed upgrade to 10GbE than 40GbE (it uses a single 25Gb/s serdes lane, as used in 100GbE, vs 4 10Gb/s lanes), and IIRC is being pushed by large datacenter shops like Google and Microsoft. There's more info at http://25gethernet.org/. I'm not sure where things are in the standardization process.nils_ - Wednesday, June 24, 2015 - link
It also has an interesting property when it comes to using a breakout cable of sorts, you could connect 4 servers to 1 100GbE port (this is already possible with 40GbE which can be split into 4x10GbE).JohanAnandtech - Wednesday, June 24, 2015 - link
Considering that the Xeon D must find a home in low power high density servers, I think dual 10 Gbit will be standard for a while. Any idea what 25/40 Gbit PHY would consume? Those 10 Gbit PHYs already need 3 Watt in idle, probably around 6-8W at full speed. That is a large chunk of the power budget in a micro/scale out server.psurge - Wednesday, June 24, 2015 - link
No I don't, sorry. But, I thought SFP+ with SR optics (10GBASE-SR) was < 1W per port, and that SFP+ direct attach (10GBASE-CR) was not far behind? 10GBASE-T is a power hog...pjkenned - Tuesday, June 23, 2015 - link
Hey Johan - just re-read. A few quick thoughts:First off - great piece. You do awesome work. (This is Patrick @ ServeTheHome.com btw)
Second - one thing should probably be a bit clearer - you were not using a Xeon D-1540. It was a ES Broadwell-DE version at 2.0GHz. The shipping product has 100MHz higher clocks on both base and max turbo. I did see a 5% or so performance bump from the first ES version we tested to the shipping parts. The 2.0GHz parts are really close to shipping spec though. One both of my pre-release Xeon D and all of the post-release Xeon D systems was nearly identical.
Those will not change your conclusions but does make the actual Intel Xeon D-1540 a bit better than the one you tested. LMK if you want me to set aside some time on a full speed version on a Xeon D-1540 system for you.