SMT Integer Performance With SPEC CPU2006

Next, to test the performance impact of simultaneous multithreading (SMT) on a single core, we test with two threads on the same core. This way we can evaluate how well the core handles SMT. 

Subtest Application type Xeon E5-2690 @ 3.8 Xeon E5-2690 v3 @ 3.5 Xeon E5-2699 v4 @ 3.6 EPYC 7601 @3.2 Xeon 8176 @ 3.8
400.perlbench Spam filter 39.8 43.9 47.2 40.6 55.2
401.bzip2 Compression 32.6 32.3 32.8 33.9 34.8
403.gcc Compiling 40.7 43.8 32.5 41.6 32.1
429.mcf Vehicle scheduling 44.7 51.3 55.8 44.2 56.6
445.gobmk Game AI 36.6 35.9 38.1 36.4 39.4
456.hmmer Protein seq. analyses 32.5 34.1 40.9 34.9 44.3
458.sjeng Chess 36.4 36.9 39.5 36 41.9
462.libquantum Quantum sim 75 73.4 89 89.2 91.7
464.h264ref Video encoding 52.4 58.2 58.5 56.1 75.3
471.omnetpp Network sim 25.4 30.4 48.5 26.6 42.1
473.astar Pathfinding 31.4 33.6 36.6 29 37.5
483.xalancbmk XML processing 43.7 53.7 78.2 37.8 78

Now on a percentage basis versus the single-threaded results, so that we can see how much performance we gained from enabling SMT:

Subtest Application type Xeon E5-2699 v4 @ 3.6 EPYC 7601 @3.2 Xeon 8176 @ 3.8
400.perlbench Spam filter 109% 131% 110%
401.bzip2 Compression 137% 141% 128%
403.gcc Compiling 137% 119% 131%
429.mcf Vehicle scheduling 125% 110% 131%
445.gobmk Game AI 125% 150% 127%
456.hmmer Protein seq. analyses 127% 125% 125%
458.sjeng Chess 120% 151% 125%
462.libquantum Quantum sim 91% 129% 90%
464.h264ref Video encoding 101% 112% 112%
471.omnetpp Network sim 109% 116% 103%
473.astar Pathfinding 140% 149% 137%
483.xalancbmk XML processing 120% 107% 116%

On average, both Xeons pick up about 20% due to SMT (Hyperthreading). The EPYC 7601 improved by even more: it gets a 28% boost on average. There are many possible explanations for this, but two are the most likely. In the situation where AMD's single threaded IPC is very low because it is waiting on the high latency of a further away L3-cache (>8 MB), a second thread makes sure that the CPU resources can be put to better use (like compression, the network sim). Secondly, we saw that AMD core is capable of extracting more memory bandwidth in lightly threaded scenarios. This might help in the benchmarks that stress the DRAM (like video encoding, quantum sim). 

Nevertheless, kudos to the AMD engineers. Their first SMT implementation is very well done and offers a tangible throughput increase. 

Single Threaded Integer Performance: SPEC CPU2006 Multi-core SPEC CPU2006
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  • Shankar1962 - Wednesday, July 12, 2017 - link

    AMD is fooling everyone one by showing more cores, pci lanes, security etc
    Can someone explain me why GOOGLE ATT AWS ALIBABA etc upgraded to sky lake when AMD IS SUPERIOR FOR HALF THE PRICE?
    Reply
  • Shankar1962 - Wednesday, July 12, 2017 - link

    Sorry its Baidu
    Pretty sure Alibaba will upgrade

    https://www.google.com/amp/s/seekingalpha.com/amp/...
    Reply
  • PixyMisa - Thursday, July 13, 2017 - link

    Lots of reasons.

    1. Epyc is brand new. You can bet that every major server customer has it in testing, but it could easily be a year before they're ready to deploy.
    2. Functions like ESXi hot migration may not be supported on Epyc yet, and certainly not between Epyc and Intel.
    3. Those companies don't pay the same prices we do. Amazon have customised CPUs for AWS - not a different die, but a particular spec that isn't on Intel's product list.

    There's no trick here. This is what AMD did before, back in 2006.
    Reply
  • blublub - Tuesday, July 11, 2017 - link

    I kinda miss Infinity Fabric on my Haswell CPU and it seems to only have on die - so why is that missing on Haswell wehen Ryzen is an exact copy? Reply
  • blublub - Tuesday, July 11, 2017 - link

    argh that post did get lost. Reply
  • zappor - Tuesday, July 11, 2017 - link

    4.4.0 kernel?! That's not good for single-die Zen and must be even worse for Epyc!

    AMD's Ryzen Will Really Like A Newer Linux Kernel:
    https://www.phoronix.com/scan.php?page=news_item&a...

    Kernel 4.10 gives Linux support for AMD Ryzen multithreading:
    http://www.pcworld.com/article/3176323/linux/kerne...
    Reply
  • JohanAnandtech - Friday, July 21, 2017 - link

    We will update to a more updated kernel once the hardware update for 16.04 LTS is available. Should be August according to Ubuntu Reply
  • kwalker - Tuesday, July 11, 2017 - link

    You mention an OpenFOAM benchmark when talking about the new mesh topology but it wasn't included in the article. Any way you could post that? We are trying to evaluate EPYC vs Skylake for CFD applications. Reply
  • JohanAnandtech - Friday, July 21, 2017 - link

    Any suggestion on a good OpenFoam benchmark that is available? Our realworld example is not compatible with the latest OpenFoam versions. Just send me an e-mail, if you can assist. Reply
  • Lolimaster - Tuesday, July 11, 2017 - link

    AMD's lego design where basically every CCX can be used in whatever config they want be either consumer/HEDT or server is superior in the multicore era.

    Cheaper to produce, cheaper to sell, huge profits.
    Reply

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