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


View All Comments

  • CajunArson - Tuesday, July 11, 2017 - link

    Would a high-end server that was built in 2014 necessarily update? Maybe not.

    Should a high-end server with a brand new microarchitecture use the most recent version of the software if it has any expectation of seeing a real benefit? Absolutely.

    If this was a GPU review and Anandtech used 2 year old drivers on a new GPU (assuming they even worked at all) we wouldn't even be having this conversation.
  • BrokenCrayons - Tuesday, July 11, 2017 - link

    Home users playing video games are in a different environment than you find in a business datacenter. There's a lot less money to be lost when a driver update causes a performance regression or eliminates a feature. Conversely, needlessly updating software in the aforementioned datacenter can result in the loss of many millions if something goes wrong. Reply
  • wallysb01 - Tuesday, July 11, 2017 - link

    Conversely, having stuff working, but unnecessarily slowly costs money as well. Its a balance, and if you're spending hundreds of thousands or even millions on a cluster/data center/what have you, you'd probably want to spend at least a little bit of time optimizing it, right? Reply
  • Icehawk - Tuesday, July 11, 2017 - link

    Most of the businesses I have worked for, ranging from 10 people to 50k, use severely outdated software and the barest minimum of patching. Optimization? HA!

    For example I work for a manufacturer & retailer currently, our POS system was last patched in 2012 by the vendor and has been replaced by at least two versions newer. We have XP machines in each of our stores as that is the only OS that can run the software.

    The above is very typical. The 50k company I worked for had software so old and deeply entrenched that modernizing it is virtually impossible. My current company is working on getting to a new product... that was new in 2012 and has also been replaced with a newer version. Whee!
  • Icehawk - Tuesday, July 11, 2017 - link

    One other thing - maybe the big shops actually do test/size but none of the places I have worked at and have been involved in do any testing, benchmarking, etc. They just buy whatever their preferred vendor gives them that meets the budget and they *think* will work. My coworker is in charge (lol) of selecting servers for a new office... he has no clue what anything in this article is. He has never read a single review, overview, or test of a processor. I could keep going on like this :( Reply
  • 0ldman79 - Wednesday, July 12, 2017 - link

    Icehawk's comments are so accurate it is scary.

    I can't tell you how many businesses running custom *nix software running in a VM on a Windows server.

    They're not all about speed. Reliability is the single most important factor, speed is somewhere down the line. The people that make those decisions and the people that drink coffee while they're waiting on the machines are very different.

    Neither understand that it could all be done so much better and almost all of them are utterly terrified at the concept of speeding up the process if it means *any* changes are made.
  • JohanAnandtech - Friday, July 21, 2017 - link

    We did test with NAMD 2.12 (Dec 2016). Reply
  • sutamatamasu - Tuesday, July 11, 2017 - link

    Glad, AMD make back again to this segment, now we can only see what can Raja to do for server market with Radeon instinct. Reply
  • Kaotika - Tuesday, July 11, 2017 - link

    So this confirms that the previous information regarding Skylake-X core configurations was wrong, and 12-core variant is in fact using HCC-core instead of LCC-core? Reply
  • Ian Cutress - Tuesday, July 11, 2017 - link

    We corrected that in our Skylake-X review. Reply

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