Conclusion

The six-core Opteron is not an alternative to the mighty Xeons in every application. The Xeons are more versatile thanks to the higher clockspeeds, higher IPC, Hyperthreading and higher bandwidth to memory. The Xeon 55xx series is clearly the better choice in OLTP, ERP, webserving, rendering and there is little doubt that it will continue to reign in the bandwidth intensive HPC workloads. There are two types of applications where we feel that the AMD six-core deserves your attention: decision support databases and virtualization.

Since the launch of ESX 3.5, VMware has said more than once that performance-critical applications such as OLTP and Decision Support Databases will perform well on top of their hypervisor. Several enhancements make the newly launched vSphere 4 an even more attractive platform for such "heavy duty" applications. Hyper-V R2 and Xen 3.4 are clearly gearing up for the same task. So it is interesting that companies are now looking into virtualizing those performance-critical applications, the applications that still got their own dedicated server a few months ago. The motivation is that virtualizing these applications would allow the complete datacenter to be managed with the same flexibility as the light, already consolidated, applications. VMotion (Xenmotion, Live Migration) can then for example be used to migrate these applications faster and much more easily.

Of course, performance-critical applications are by definition more demanding when it comes to processing power. That is exactly what vApus Mark I measures: how well do performance-critical applications perform when they are virtualized? This is a relatively “new” market where the AMD 2435 shines. The new Opteron 2435 at 2.6 GHz was a pleasant surprise on vApus Mark I: it keeps up with more expensive Xeons on ESX 3.5 update 4 while consuming less, and offers a competitive performance/watt and performance/price ratio on vSphere 4. The six-core Opteron is about 11 to 30% slower on vSphere 4 than the 2.93 GHz Xeon X5570 but the overall cost of the Istanbul platform is significantly lower (DDR-2 versus DDR-3) and the 2.6 GHz 2435 consumes less power in a virtualized environment (*). On the condition that you optimize your hypervisor well to take advantage of the six cores (cell size is for example one critical optimization), we feel that the six-core Opteron is a worthy opponent for the Xeon “Nehalem” in this market. We tested only the 2435 versus the X55xx series. The Xeon E5540 2.53 GHz versus the Opteron 2431 2.4 GHz may show a slightly different view… the six-core Opteron and Xeon are both very competitive in this area, other factors than performance/price/power might conclude the decision. There is no clear winner in this part of the market, but the big news is of course that AMD offers a worthy alternative.

VMmark tells us that the Xeon X55xx handles large amounts of VM’s much better. With “light VM’s” the amount of memory you can place in a server plays in many cases a more important role than the CPU. In that case you might be better off with a low power quad-core instead of a six-core or high-clocked quad-core.

Lastly, the six-core Opteron will be a formidable competitor in the 4P market segment. But that is for a later article.

(*) Virtualized servers do not run idle very often.
 
A big thanks to Tijl Deneut for sacrificing his weekend to keep testing and checking together with me. Anand and Liz helped to get this article online, thanks!
Power Consumption & Market Analysis
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  • duploxxx - Wednesday, June 3, 2009 - link

    ESX 4 should add IOMMU to the AMD istanbul platform, not sure how far this is implemented in the beta esx4 builds.

    Are you using the paravirtualization scsi driver in the new esx4 platform, I would expect bigegr differences between 3.5 and 4 and not just because EPT is included in esx4 together with enhanced HT.

    for the rest very good thorough review.

    The only thing I always miss in reviews is that although it is good to test the fastest out there, it is now where near the most deployed platform, you rather should look at the 5520-5530 against 2387 - 2431 as the mid range platform that will be deployed in a wide range of systems, this will have a much healthier performance/price/power platform then the top bin. Even the 5570 is not supported in all OEM platforms for the TDP range.
    Reply
  • Adul - Monday, June 1, 2009 - link

    I do not see oracle running on top of windows all that often. It is normally running on some *nix OS. How about running the same benchmark on say RHEL instead? Reply
  • InternetGeek - Monday, June 1, 2009 - link

    There's actually an odd bug on Oracle's DB that makes it run faster on Windows than on Linux. Search on the internet and you'll find info about it.

    In the other hand, in my now 9 years in the IT industry I've only come across one Oracle DB running on HP-UX. Everything else (Sybase, MySQL, etc) runs on Windows.
    Reply
  • LizVD - Friday, June 5, 2009 - link

    Could you provide us with a link for that? I'd like to see if this "bug" corresponds with the behaviour we're seeing on our tests. Reply
  • Nighteye2 - Monday, June 1, 2009 - link

    You give a good description of how it works and how it has so much benefit, but then you benchmark only dual-socket servers?

    It would be fairer to also test and compare octo-socket servers - to see the real impact of that HT assist feature.
    Reply
  • phoenix79 - Monday, June 1, 2009 - link

    Completely agreed (I was typing up a comment about this too when yours popped up)

    I'd love to see some 4-way VMWare scores
    Reply
  • ltcommanderdata - Monday, June 1, 2009 - link

    Yes. Nehalem is in a great position in the DP market, but isn't yet available in MP. It'd be great to see six-core Dunnington and six-core Istanbul go head to head. Conveniently their highest models have similar clock speeds at 2.66GHz and 2.6GHz respectively although Dunnington would be a lot more power hungry and although I don't remember their prices, probably more expensive too. Reply
  • JohanAnandtech - Tuesday, June 2, 2009 - link

    Dunnington vs Istanbul coming up ... But we are going to take some time to address the shortcomings of this "deadline" article such as better power consumption readings. Reply
  • solori - Monday, June 1, 2009 - link

    "Notice that HT-assist is a performance killer in 2P configurations: you remove two times 1 MB of L3-cache, which is a bad idea with 8 VM’s hitting your two CPUs."

    BIOS guidance suggests that HT Assist be disabled by default on 2P systems, and enabled only for specialized workloads. So that begs the question: Were vAPUS tests performed with or without HT Assist in the 2P configuration? It was not clear.

    I assume AMD-V and RVI were enabled for ALL workloads in ESX 3.5 and 4.0 (forced for 32-bit workloads.) Is this accurate? Based on the number of ESX 3.5 installations out there, this probably should be clearly stated...

    I do want to take issue with your memory sizing and estimates on vCPU loading. Let me put it this way: while Nehalem-EP has better memory bandwidth and SMT threads, Opteron has access to abundant memory. Therefore, it does not make sense - for example - to be OK with enabling SMT but then constrain the benchmark to 24GB due to a Xeon memory limitation.

    I would urge you to look at 48GB configurations on Xeon and Istanbul for your comparison systems. By the way, in consolidation numbers, this makes a significant reduction in $/VM with only a minor increase in per-system CAPEX.

    Another interesting issue you touched on is tuning and load balance. Great job here. These are "black magic" issues that - as you noted - can have serious effects on virtualization performance (ok, scheduling efficiency.) Knowing your platform's balance point(s) is critical to performance sensitive apps but not so critical for light-load virtualization (i.e. not performance sensitive.)

    It sounds like your learning - through experimentation with vAPUS - that virtualization testing does not predict similar results from "similarly configured machines" where performance testing is concerned. In fact, the "right balance" of VM's, memory and vCPU/CPU loading for one system may be on the wrong side of the inflection point for another.

    All and all, a very good article.
    Reply
  • JohanAnandtech - Tuesday, June 2, 2009 - link

    "this probably should be clearly stated... "

    Good suggestion. I adapted the article. RVI and EPT are always on if possible (so also 32 bit). HT-assist is of always on "Auto" (so off) unless we indicate otherwise.

    "Therefore, it does not make sense - for example - to be OK with enabling SMT but then constrain the benchmark to 24GB due to a Xeon memory limitation. "

    1) You must know that vApus Mark I uses too much memory for the webportals. They can run without any performance loss in 2 GB, even 1 GB. So as we move up on the number of tiles we run, it is best to reclaim the wasted memory.

    2) I agree that a price comparison should include copious amount of memory (48 GB or so).

    3) We don't have more than 24 GB DDR-3 available right now. It would be unfair to force the system to swap in a performance comparison.

    "Opteron has access to abundant memory". What do you mean by this? Typical 2P Opterons have 64 GB, 2P Nehalems 72 GB as upper limit?

    "In fact, the "right balance" of VM's, memory and vCPU/CPU loading for one system may be on the wrong side of the inflection point for another"

    Great comment. Yes, that makes it even more complex to compare two systems. That is why we decided to show 2 datapoints for the 2 tile systems.

    Collin, thanks for the excellent comments. It is very rewarding to notice that people take the time to dissect our hard work. Even if that means that you find wrinkles that we have to iron out. Great feedback.




    Reply

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