SPEC CPU2006 Cont: Per-Core Performance w/SMT

Moving beyond single-threaded performance, multi-threaded performance within the confines of a single core is of course also important. The Vulcan CPU architecture was designed from the start to leverage SMT4 to keep its cores occupied and boost their overall throughput, so this is where we'll look next.

SPEC CPU2006: Single Core w/SMT
Subtest
SPEC CPU2006
Integer
Application Type Cavium
ThunderX
2 GHz
gcc 5.2
1 thread
Cavium
ThunderX2
@2.5 GHz
gcc 7.2
4 threads
Xeon
8176
@3.8 GHz
gcc 7.2
2 threads
Thunder
X2
vs
Xeon 8176
Thunder
X2
vs
ThunderX
400.perlbench Spam filter 8.3 24.1 50.6 48% 290%
401.bzip2 Compression 6.5 22.9 31.9 72% 350%
403.gcc Compiling 10.8 35 38.1 92% 330%
429.mcf Vehicle scheduling 10.2 52.4 50.6 104% 510%
445.gobmk Game AI 9.2 25.1 35.6 71% 270%
456.hmmer Protein seq. analyses 4.8 26.7 41 65% 560%
458.sjeng Chess 8.8 22.4 37.1 60% 250%
462.libquantum Quantum sim 5.8 83.6 83.2 100% 1440%
464.h264ref Video encoding 11.9 34 66.8 51% 290%
471.omnetpp Network sim 7.3 31.1 41.1 76% 440%
473.astar Pathfinding 7.9 27.2 33.8 80% 340%
483.xalancbmk XML processing 8.4 33.8 75.3 45% 400%

First of all, the ThunderX2 core is a massive improvement over the simple ThunderX core. Even excluding libquantum – that benchmark could easily run 3 times faster on the older ThunderX core after some optimization and compiler improvements – the new ThunderX2 is no less than 3.7 times faster than its older brother. This kind of an IPC advantage makes the original ThunderX's 50% core advantage all but irrelevant.

Looking at the impact of SMT, on average, we see that 4-way SMT improves the ThunderX2's performance by 32%. This ranges from 8% for video encoding to 74% for pathfinding. Intel meanwhile gets a 18% boost from their 2-way SMT, ranging from 4% to 37% in the same respective scenarios.

Overall, a boost of 32% for the ThunderX2 is decent. But it does invite an obvious comparison: how does it fare relative to another SMT4 architecture? Looking at IBM's POWER8, which also supports SMT4, at first glance there seems to be some room for improvement, as the POWER8 sees a 76% boost in the same scenario.

However this isn't entirely an apples-to-apples comparison, as the IBM chip had a much wider back-end: it could issue 10 instructions while the ThunderX2 core is limited to 6 instructions per cycle. The POWER8 core was also much more power hungry: it could fit only 10 of those ultra-wide cores inside a 190W power budget on a 22 nm process. In other words, further increasing the performance gains from using SMT4 would likely require even wider cores, and in turn seriously impact the total number of cores available inside the ThunderX2. Still, it is interesting to put that 32% number into perspective.

Single-Threaded Integer Performance: SPEC CPU2006 Java Performance
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  • imaheadcase - Sunday, May 27, 2018 - link

    Yah i tried that for a bit, it worked ok. But was not foolproof, it missed some stuff.
  • repoman27 - Wednesday, May 23, 2018 - link

    Just to provide a counter point, this article made my day. And that’s coming entirely from intellectual curiosity—I don’t plan on deploying any servers with these chips in the near future. I always enjoy Johan’s writing, and was really looking forward to seeing how ThunderX2 would stack up. Many people are convinced that ARM is really only suitable in low power / mobile scenarios, but this is the chip that may finally prove otherwise. That has significant ramifications for the entire industry (including the consumer space), especially when you consider that Cavium could put out a TSMC 10nm or even 7nm shrink of ThunderX2 before Intel can get off of 14nm.
  • HStewart - Wednesday, May 23, 2018 - link

    This does not proved that ARM is suitable in higher end space - look at the core specific speed - it extremely low compare to Intel and AMD server chips. Keep in mind it takes 128 total cores - running at 4SMT system. And what about other operations - what about Virtual Machine situation - where you have many virtual x86 machines on VMWare server,

    How about high end mathematical and vector logic?

    It does seem like ARM can run more threads - but maybe Intel or AMD has never had the need to

    I think this latest Core battle is silly - I think it really not the number of cores you have but combination of type and speed of cores along with number of cores.
  • Wilco1 - Wednesday, May 23, 2018 - link

    It certainly does prove that Arm can do high end servers - the results clearly show IPC/GHz is very close on SPECINT. Base clock speeds are the same as the Intel cores, and that's the speed the server runs at when not idle. But there are more cores as you say, so who will win is obvious.

    Now imagine a next-gen 7nm version before Intel manages 10nm. Not a pretty picture, right?
  • HStewart - Wednesday, May 23, 2018 - link

    Ok I have learn to agree to disagree with some people

    Can this server run the VMWare server

    https://kb.vmware.com/s/article/1003882

    The answer is no - just one example - many more,

    On 10nm - it not number that matters - it technology behind it - Intel supposely has a i3 and Y based for CannonLake coming this year - probably more.
  • Wilco1 - Wednesday, May 23, 2018 - link

    There are plenty of VMs for Arm, so virtualization is not an issue.

    10nm will be behind 7nm even if it ends up as originally promised and not using relaxed rules to become viable for volume production.
  • ZolaIII - Thursday, May 24, 2018 - link

    When optimized for SIMD NEON extension things changed dramatically. All tho NEON isn't exactly the best SIMD never the less number's speak for them self.
    https://blog.cloudflare.com/neon-is-the-new-black/
    Tho Centriq is a bit pricier, bit overly slower than this but main point is it whose built on comparable lithography to current Intel's 14nm. So you get cheaper hardware, which can be packaged tighter & will consume much less power while being compatible regarding the performance. Triple win situation (initial cost, cost of ownership and scaling) but it still isn't turn key one whit isn't crucial for big vendor server farms anyway.
  • name99 - Thursday, May 24, 2018 - link

    ARM (and this particular chip) aren't trying to solve every problem in the world. They're trying to offer a better (cheaper) solution for a PARTICULAR subset of customers.

    If you think such customers don't exist, then why do you think Intel has such a wide range of Xeons, including eg all those Xeon Silvers that only turbo up to 3GHz? Or Xeon Gold's that max out at 2.8GHz?
  • lmcd - Thursday, May 24, 2018 - link

    Second page: supports SR-IOV, which is important for KVM and Xen. If you're not aware, Xen and KVM are powerful virtualization solutions that cover the feature set of VMWare quite nicely.
  • HStewart - Wednesday, May 23, 2018 - link

    "I really think Anandtech needs to branch into different websites. Its very strange and unappealing to certain users to have business/consumer/random reviews/phone info all bunched together."

    I different in this - I don't think AnandTech should concentrate on just gaming in focus - this is rather old school - I am not sure about mobile phones in the mess of all this

    But comparing ARM cpu's to Intel/AMD is interesting subject. It basically RISC vs CISC discussion - yes RISC can do operations quicker in some cases - but by definition of the architecture they are Reduce in what they do. Fox example it would take RISC a ton of instructions to executed a single AVX style operation.

    This article is closest I have seen in comparing ARM vs x86 base machines - but even though I see some holes - it comes close - but having just be Linux based leaves out why people purchase such machine - I think Virtual Machine server is huge - but like everything else on the internet that is just an opinion

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