Memory Subsystem: Bandwidth

Let's set the stage first and perform some meaningful low level benchmarks. First, 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

The results are expressed in GB per second. Note that we also tested with gcc 4.8.1 and compiler options

-O3 –fopenmp –static

Results were consistently 20% to 30% lower with gcc, so we feel our choice of Open64 is appropriate. Everybody can reproduce our results (Open64 is freely available) and since the binary is capable of reaching higher speeds, it is easier to spot speed differences.

Stream Triad

We get a 13% increase in bandwidth, which is a result of the faster SMI interface (3.2 GT/s instead 2.67 GT/s). Intel did a good job here: it is not easy to keep bandwidth scaling with the socket count. 

SAP S&D Benchmark Single-threaded Integer Performance and our first POWER8 benchmark
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  • TheSocket - Friday, May 8, 2015 - link

    They sure wouldn't lose the x86-64 license since they own it and Intel is licensing it from AMD.
  • melgross - Saturday, May 9, 2015 - link

    But without the license from Intel, it is worthless. There's also the question of how that works. I believe that Intel doesn't need to license back the 64 bit extensions.
  • Kevin G - Monday, May 11, 2015 - link

    This one of the reasons why it would be in Intelsat best interest to let AMD be bought out with the 32 bit license intact. The 64 bit license/patents going to a third party that doesn't want to share would be a dooms day scenario for Intel. Legally it wouldn't affect anything currently on the market but it'd throw Intel's future roadmap into the trash.
  • Death666Angel - Saturday, May 9, 2015 - link

    Pretty sure some regulatory bodies would step in if Intel were the only x86 game in town. And x86-64 is AMD property.
  • JumpingJack - Saturday, May 9, 2015 - link

    Any patents on x86 are long expired, AMD only owns the IP related to the extension of the x86 not the instruction set.
  • patrickjp93 - Monday, May 11, 2015 - link

    Not true. The U.S. government has them locked up under special military-based protections. Absolutely no one can make and sell x86 without Intel's and the DOD's permission.
  • Kevin G - Monday, May 11, 2015 - link

    Got a source for that?

    I know that DoD did some validation on x86 many years ago. (The Pentium core used by Larrabee had the DoD changes incorporated.)
  • haplo602 - Friday, May 8, 2015 - link

    hmm ... where's the RAS feature comparison/test ? did I miss it in the article ?
  • TeXWiller - Friday, May 8, 2015 - link

    In the E7v3 vs POWER comparison table, there should be 32 PCIe lanes instead 40 in the Xeon column.
  • TeXWiller - Friday, May 8, 2015 - link

    Additionally, it is the L3 in POWER8 that runs half of the core speed. L2 runs at the core speed.

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