STARS Euler3D CFD

The STARS Euler3D CFD benchmark got popular thanks to Scott of Techreport.com. It is a computational fluid dynamics (CFD) benchmark based on the STARS Euler3D structural analysis routines developed at CASELab, the Computational AeroServoElasticity Laboratory at Oklahoma State University. Since the benchmark has been used for years by Scott, we felt it was a good place to start our HPC benchmarking adventure: we could check if our results are in the right ballpark.

The benchmark is downloadable and described in great detail here. The benchmark score is reported as a CFD cycle frequency in Hertz, with higher results being better.

Stars Euler 3D CFD: maximum score

The Xeon E7 scales quite nicely on the condition that you disable Hyper-Threading. The benchmark is able to take advantage of Hyper-Threading, which can be seen on the dual Xeon system. However, the threads work on the same data grid, so the more threads, the more locking contention rears its ugly head. Here's a more detailed look at scaling with the number of threads:

The Hyper-Threading enabled Xeon X5670 performs worse than the non-HT setup until we run more than 12 threads. Once we do that it can offer a decent performance boost (17%). The benchmark however does not scale enough to take advantage of 80 threads. Hyper-Threading offers better resource utilization but that does not negate the negative performance effect of the overhead of running 80 threads. Once we pass 40 threads on the E7-4870, performance starts to level off and even drop.

Of course, you are probably more interested in the other server result. What happened to the Opteron scores? Why is the 48 core Opteron five times slower than the 40 core Xeon E7? Let's investigate further.

Cinebench Release 11.5 Investigating the Opteron Performance Mystery
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  • Phynaz - Friday, September 30, 2011 - link

    If you are overclocking in a business environment, what other moronic decisions has your company made?

    When does the going out of business sale start?
  • MrSpadge - Friday, September 30, 2011 - link

    Don't condemn him blindly. By overclocking they can get substantially more performance from a similar budget. that's more efficiency - if done right.

    The question is "what happens in case of failure". If it's just a crashing machine, the rendering can be repeated by another one and this machine can be tuned down a bit. If it's a visual artefact during rendering, the redering can be repeated by any machine and this machine tuned down a bit. What else could go wrong in rendering? Obviously you wouldn't want to OC your web server or database..

    BTW: there was an article here some time ago, showing Cyrix doing their testing on OC'ed i7s.

    MrS
  • Kvarta - Tuesday, October 4, 2011 - link

    Don't be so sure. Recently You can see standard desktop CPU beating expensive Xeons in professional applications. Example:
    http://www.solidworks.com/sw/support/shareyourscor...
    So You don't need to buy very expensive DELL or other workstation, instead go to PC boutique near the corner :)
  • JohanAnandtech - Saturday, October 1, 2011 - link

    This was not meant to be a professional rendering test. It was more an experiment to give the enthusiasts an idea what these servers are capable off. If you have a suggestion on which animation we should use in our benchmarking scenario's let me know. I have solid background in the "web- database - virtualization" field (I have been active in the field for more than 10 years now, teaching and consulting) , but rendering and HPC is something I only know from a benchmarking background :-).
  • WeaselITB - Friday, September 30, 2011 - link

    I'll echo the other sentiments here. If a Xeon system renders something twice as fast as the Opteron system, but takes five times the power draw to do it, it's a net-win for the Opteron system. Performance / watt would be a useful metric in these comparisons, especially as systems like these will be going in data rooms where excess wattage = excess heat = excess money.

    I would also be interested to know what a comparision would be between a "big iron" system like this versus a "traditional" render farm composed of some Core i7 machines.

    Awesome review, though! I'm especially happy with the fact that you didn't just say "Oh, the Operteron kinda sucks in this test. Oh well." but actually took a look deeper into what's going on with the benchmark and the workload. THAT's the type of analysis that makes me keep coming back to AnandTech. :-)

    Thanks,
    -Weasel
  • JarredWalton - Friday, September 30, 2011 - link

    Pretty sure perf/Watt isn't going to be in Opteron's favor, but there's a lot of stuff you need to account for. Johan did some measurements of power use on these servers previously (http://www.anandtech.com/show/4285/6), but as pointed out the Intel setup has a lot more RAS features and such that could be adding to the power use. Even so, the "load" power measured (using vAPUS, which may use less than something like 3D rendering) is around 875W (HT off) to 920W for the Intel E7-4870 server compared to around 590W for the Opteron 6174 server.

    In terms of perf/Watt, if those figures are relatively close for the benchmarks Johan has done here, then the best scores in Cinebench give 0.0355 CB/Watt for E7-4870 vs. 0.0425 CB/Watt for the Opteron 6174 -- and again, note that the 64-thread limit (tested with 40) means CB11.5 isn't able to make maximum use of the Intel platform. For the second test, best-case we measure 0.0194 CFD/W for Intel compared to 0.0145 CFD/W for AMD. So AMD wins in 3D rendering by 20% and Intel wins in the Euler3D CFD test by 34%, at least given the current estimates.

    My gut feeling is that if all other elements and features were identical, other than the necessary chipset and CPU differences (e.g. the PSU, amount of RAM, HDDs, fans, RAS features, etc.), the difference in power draw for the two platforms should be within 100W, not the up to 340W spread measured in the earlier article. (There's also a 310W difference at idle, which gives some indication of all the other things that appear to be running on the Intel setup, as normal idle power looking at just the CPUs should be very nearly equal.) So these figures I list here are specific to the Intel Quanta QSCC-4R and Dell PowerEdge R815 and may not hold for other AMD/Intel servers. In other words, take with a grain of salt.
  • RandomUsername3245 - Friday, September 30, 2011 - link

    The intel compiler is a very good compiler for Intel CPUs, but in the past it was well known for producing poor quality binaries for non-Intel CPUs. I would still be wary of benchmarking Intel vs. AMD when running code compiled with Intel's compiler.

    FWIW, I heard a while ago that Intel was "officially" going to stop artificially penalizing AMD CPUs that run Intel-compiled code.
  • James5mith - Friday, September 30, 2011 - link

    Just a note:

    We are doing some in house testing for high end database testing using solid state storage connected via infiniband to multisocket servers.

    An example:

    Dell R910
    4x 8C/16T X7560 2.26GHz Xeon CPU (32C/64T total)
    512GB RAM
    2x 146GB 15K SAS hdd's in RAID1 (OS)
    2x Mellanox QDR Infiniband 40Gbps adapters

    Hooked up to some seriously fast external flash storage, we got around 6GB/s+. This allowed us to do massively multi-threaded workloads, like building an index on a 2TB database.

    During these tests, we can max out all 64 Threads and put the entire box under 100% load. It was during these tests we found out that Dell has a flawed implementation of the Intel SpeedStep technology which keeps the fans from ramping up under load.

    Without the fast storage, we could never have fully stress tested the box.
  • mczak - Friday, September 30, 2011 - link

    I think part why the opteron has bad scaling without interleaving and xeon does not is not just due to the coherence engine.
    Don't forget that while both have 4 sockets the Opteron is a 8 node system. The article states that there are "4 memory controllers" and "3 out of 4 operations traverse the HT link" which isn't really true as there are 8 memory controllers (and 7 out of 8 operations traverse HT, though some of them are internal HT links).
    You can see that this makes a difference with the bad scaling from 6 to 12 threads (though not as bad as with even more threads...).
  • extide - Friday, September 30, 2011 - link

    Dont forget the Xeon E7 is 4 sockets with 4 memory channels each.

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