OpenFoam

Computational Fluid Dynamics is a very important part of the HPC world. Several readers told us that we should look into OpenFoam and calculating aerodynamics that involves the use of CFD software.

We use a realworld test case as benchmark. All tests were done on OpenFoam 2.2.1 and openmpi-1.6.3.

We also found AVX code inside OpenFoam 2.2.1, so we assume that this is one of the cases where AVX improves FP performance. 

Actiflow OpenFoam Benchmark

HPC code is where the Xeon E5 makes a lot more sense than the cheaper Xeons. The Xeon E5 is no less than 80% faster with 50% more cores than the Xeon D.  In this case, the Xeon D does not make the previous Xeons E3 look ridiculous: the Xeon D runs the job about 33% faster. Let us zoom in. 

OpenFoam 1-8 threads

OpenFoam scales much better on the Xeon E5, and we've seen previously that a second CPU boost performance by 90% offering near linear scaleability. Double the number of cores again and you get another very respectable 60%. Eight cores are 34% faster than four, and 4.1 times faster than one. 

Compares this to the horrible scaling of the Xeon E3 v2: 4 cores are slower than one. The Xeon E3 v3 fixed that somewhat, and doubles the performance over the same range. The eight cores of the Xeon D are about 2.8 times faster than one - that is decent scaling but nowhere near the Xeon E5. There are several reasons for this, but the most obvious one is that the Xeon E5 really benefits from the fact that it has almost twice the amount of bandwidth available. To be fair, Intel does not list HPC as a target market for the Xeon D. If the improved AVX2 capabilities and the pricing might have tempted you to use the Xeon D in your next workstation/HPC server, know that the Xeon D can not always deliver the full potential of the 8 Broadwell cores, despite having access to DDR4-2133.

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  • extide - Wednesday, June 24, 2015 - link

    So, I was thinking last night, that this chip is THE PERFECT enthusiast chip! All Intel needs to do is release an unlocked and socketed version (although that would be complex because there is currently no platform for it ...) although if we could get at least an unlocked version on an enthusiast style board it would be awesome.

    Think about it:
    8 Broadwell cores -- Great!
    12MB L3 -- Great!
    24 Lanes PCIe 3.0 -- More than 16 or even skylakes rumored 20, pretty good. You could do things like 16x + 8x, or 8x + 8x + 4x + 4x (the two 4x being m.2 ssd's) which would support CF or SLI quite well and some fast ssd's.
    2ch DDR4 -- plenty for gaming and most enthusiast applications
    Dual 10GbE -- Just added Gravvy here, but would def help adoption of 10g in the enthusiast realm.

    COME ON INTEL!!
  • extide - Wednesday, June 24, 2015 - link

    Also, I forgot to add:

    This would be a great intermediate between the current regular consumer stuff (LGA 115x) and HPDE (LGA 2011x) -- A lot of people really see the LGA 2011 platform as overkill, even for enthusiasts, and it gets so expensive, with quad channel ddr4 and all that. This chip just seems to make so much sense. Now if intel priced it no more than the $500 mark, that would be awesome. Imagine, if AMD was more competitive, we might actually have that5 scenario.... Hopefully Zen is just great!
  • Namisecond - Saturday, June 27, 2015 - link

    Intel's tray price for this chip is listed at $199 for the 4-core and $581 for the 8-core. The price for the CPU+motherboard is almost $1K for the 8 core. which indicates the problem is not in the price of the chip itself.

    If you want cheap and low power consumption, I'd direct you to the S1150 platform with Xeon E3 V3 "L" series (13-45W) processors.
  • spikebike - Wednesday, June 24, 2015 - link

    For a home machine, small server, workstation, or similar the Xeon D 1520 looks even better. Faster clock, 1/3rd the price, same maximum ram, ecc, etc. Sure it's got 4 cores/8threads instead of more, but for many use cases that's not a big limitation. In quite a few cases spending the $400 different on RAM or SSDs will make a bigger difference.
  • hifiaudio2 - Thursday, June 25, 2015 - link

    Where can you get a 1520? Google searching is not finding anything for sale...
  • hifiaudio2 - Thursday, June 25, 2015 - link

    If I cannot find the 1520 for sale, what is the best bang for the buck i3 and MB combo (want to use ECC ram as well) for a Media server/transcode/nas? Low TDP, etc..
  • jaziniho - Thursday, June 25, 2015 - link

    Any word on whether HP plan to make a Moonshot cartridge featuring Xeon D? the 45W TDP seems to match up with some of the previous chips they have used.
  • jeffsci - Monday, June 29, 2015 - link

    Why do the results use a variety of OSS compilers? For an Intel Xeon processor, the Intel compilers are the most reliable. Is Open64 actively developed for Intel processors? And switching from GCC 4.8 to 4.9 with different flags...how is this even remotely scientific?
  • needforsuv - Saturday, July 11, 2015 - link

    so they just done to the 'regular' 4/8 i7/e3 what they did to the C2D in making the C2Q but more sophisticated I like it now wheres that lga 115x 8 core
  • tabascosauz - Sunday, July 19, 2015 - link

    I hope that Mr. de Gelas will continue to learn and improve as a writer, because the grammar in this article is, in numerous places, rather iffy and AT has traditionally excelled in delivering detailed, grammatically correct content.

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