Memory Subsystem Bandwidth

While the Xeon E5 has ample bandwidth for most applications courtesy of the massive quad-channel memory subsystem, the Xeon E3 and Atom C2000 only have two memory channels. The Xeon E3 and Atom C2000 also do not support the fastest DRAM modules (DDR3-1600, Xeon E5: DDR4-2133), so memory bandwidth can be a problem for some applications.

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.

Stream Triad

First of all, we should note that the clock speed of the CPU has very little influence on the Stream score. Notice the small difference (12.7%) between the Xeon E3-1240 that can boost to 3.6GHz and the Xeon E3-1230L that is limited to 2.3GHz (Turbo Boost with four cores busy).

The Xeon E3-1200 v3 is slightly more efficient than the Xeon E3-1200 v2; we measured a 7% bandwidth improvement. The Xeon E3 also offers up to 33% more bandwidth than the Atom C2750 with the same DIMMs.

To do an apples-to-apples comparison with the X-Gene 1, we compiled the same OpenMP enabled Stream benchmark (O3 –fopenmp –static).

Stream Triad GCC 4.8.2

The Xeon E3 has the most efficient memory controller: it can extract almost as much bandwidth as the quad-channel memory controller of the X-Gene and about 46% more than the Atom. Our guess is that the X-Gene still has quite a bit of headroom to improve the memory subsystem. There is work to be done on the compiler side and on the hardware.

 

Benchmark Configuration Memory Subsystem: Latency
POST A COMMENT

47 Comments

View All Comments

  • gdansk - Monday, March 09, 2015 - link

    xgene is not looking so great. Even if it is 50% more efficient as they promise they'll still be behind Atom. Reply
  • Samus - Monday, March 09, 2015 - link

    HP Moonshot chassis are still *drool* Reply
  • Krysto - Monday, March 09, 2015 - link

    The main problem with the non-Intel systems is not only that they use older processes compared to Intel, but that they use older processes even compared to the rest of the non-Intel chip industry. AMD is typically always behind 1 process node among non-Intel chip makers. If they'd at least use the cutting edge processes as they become available from non-Intel processes, maybe they'd stand a chance, especially now that the gap in process technologies is shrinking. Reply
  • Samus - Monday, March 09, 2015 - link

    AMD simply isn't as bad as people continually make them out to be. Yes, they're "behind" Intel but it's all in the approach. We are talking about two engineering houses that share nothing in common but a cross licensing agreement. AMD has very competitive CPU's to Intel's i5's for nearly half the price, but yes, they use more power (at times 1/3 more.)

    But facts are facts: AMD is the second high-tech CPU manufacture in the world. Not Qualcomm, not Samsung. It's pretty obvious AMD engineering talent spreads more diversity than anyone other than Intel, and potentially superior to Intel on GPU design (although this has obviously been shifting over the years as Intel hires more "GPU talent.")

    AMD in servers is a hard pill to swallow though. If purchasing based on price alone, it can be a compelling alternative, but for rack space or low-energy computing?
    Reply
  • Taneli - Tuesday, March 10, 2015 - link

    AMD doesn't even make it in top 10 semiconductor companies in sales. Qualcomm is three, Samsung semicondutors six and Intel almost ten times the size of AMD.

    Outside of the gaming consoles they are being completely overrun by competition.
    Reply
  • owan - Tuesday, March 10, 2015 - link

    I'm sorry, at one point I was an AMD fanboy, back when they actually deserved it based on their products, but you just sound like an apologist. Facts are the facts, FX processors aren't competitive with i5's in performance or power or performance/$ because they get smacked so hard they can't be cheap enough to make up for it. Their CPU designs are woefully out of date, their APU's are bandwidth starved and use way too much power to be useful in the one place they'd be great (mobile), and their lagging process tech means theres not much better coming on the horizon. I don't want to see them go, but at the rate ARM is eating up general computing share, it won't be long before AMD becomes completely irrelevant. It will be Intel vs. ARM and AMD will be an afterthought. Reply
  • xenol - Wednesday, March 11, 2015 - link

    Qualcomm is used in pretty much used in most cell phones in the US to the point you'd think Qualcomm is the only SoC manufacturer. I'm pretty sure that's also how it looks in most of the other markets as Korea. Plus even if their SoCs aren't being used, they're modems are heavily used.

    If anything, Qualcomm is bigger than AMD. Or rather, Qualcomm is the Intel of the SoC market.
    Reply
  • xenol - Wednesday, March 11, 2015 - link

    [Response to myself since I can't edit]
    Qualcomm's next major competitor is Apple. But that's about it.

    Also I meant to say other markets except Korea.
    Reply
  • CajunArson - Monday, March 09, 2015 - link

    Bear in mind that the Atom parts were commercially available in 2013, so they are by no means brand-new technology and the 14nm Atom upgrades will definitely help power efficiency even if raw performance doesn't jump a whole lot.

    Anandtech is also a bit behind the curve because Intel is about to release Xeon-D (8 Broadwell cores and integrated I/O in a 45 watt TDP, or lower), which is designed for exactly this type of workload and is going to massively improve performance in the low-power envelope sphere:

    http://techreport.com/review/27928/intel-xeon-d-br...
    Reply
  • SarahKerrigan - Monday, March 09, 2015 - link

    14nm server Atom isn't coming.

    http://www.eetimes.com/document.asp?doc_id=1325955

    "Atom will become a consumer only SoC."
    Reply

Log in

Don't have an account? Sign up now