Comparing Benchmarks: AT vs IBM

Before we close things out, let's spend a moment summarizing our results and comparing the performance we saw to the kind of performance advantages that IBM advertises POWER8 is capable of.

From a high level perspective, the S822L is more expensive and consumes a lot more power than a comparable Xeon system.

With limited optimization and with the current Ubuntu 15.04, the performance-per-watt ratio favors Intel even more as the POWER8 barely outperforms the very efficient 120W TDP Xeons. So there is no denying that the Intel systems offer a superior performance/watt ratio.

However, it would be unfair to base our judgement on our first attempt as we have to admit this our first real attempt to benchmark and test the POWER8 platform. It is very likely that we will manage to extract quite a bit more performance out of the system on our second attempt. IBM POWER8 also has a big advantage in memory bandwidth. But we did not manage to port OpenFOAM to the POWER platform, probably the most likely candidate for leveraging that advantage.

We are less convinced that the POWER8 platform has a huge "raw CPU compute advantage," contrary to what for example IBM's SPECJBB (85% faster ) and SAP (29% faster) results seem to suggest.

For example, IBM's own SPECjEnterprise®2010 benchmarking shows that:

SAP is "low IPC" (hard to run many instructions in parallel in one thread) software that benefits much from low latency caches. The massive L3-cache (12-cores, 96 MB) and huge thread count are probably giving the IBM POWER8 the edge. The RAM bandwidth also helps, but in a lesser degree. IBM clearly built POWER8 with this kind of software in mind. We had individual threadcount intensive benchmarks (LZMA decompression) and L3-cache sensitive benchmarks (ElasticSearch), but t o be fair to IBM, none of our benchmarks leveraged the three strongest points (threadcount, L3-cache size and memory bandwidth) all at once like SAP.

SPECJBB2013 has recently been discontinued as it was not reliable enough. We tend to trust the jEnterprise test a lot more. In any case, the best POWER8 has a 17% advantage there.

Considering that the POWER8 inside that S824 has 20% more cores and a 3% higher clockspeed, our 3.4 GHz 10-core CPU would probably be slightly behind the Xeon E5-2697 v3. We found out that the 10-core POWER8 is slightly faster than Xeon E5-2695 v3. The Xeon E5-2695 v3 is very similar to the E5-2697 v3, it is just running at a 10% lower clockspeed (All core turbo: 2.8GHz vs 3.1GHz). So all in all, our benchmarks seems to be close to the official benchmarks, albeit slightly lower.

Closing Thoughts: A Mix of Xeon "E5" and "E7"

So let's sum things up. The IBM S822L is definitely not a good choice for those looking to lower their energy bills or operate in a location with limited cooling. The pricing of the CDIMMs causes it to be more expensive than a comparable Xeon E5 based server. However, you get something in return: the CDIMMs should offer higher reliability and are more similar to the memory subsystem of the E7 than the E5. Also, PCIe adapters are hot-pluggable on the S822L and can be replaced without bringing down the system. With most Xeon E5 systems, only disks, fans and PSU are hot-pluggable.

In a number of ways then, the S822L is more a competitor to dual Xeon E7 systems than it is to dual Xeon E5 systems. In fact, a dual Xeon E7 server consumes in the 600-700W range, and in that scenario the power usage of S822L (700-800W) does not seem outrageous anymore.

The extra reliability is definitely a bonus when running real time data analytics or virtualization. A failing memory chip may cost a lot when you running fifty virtual machines on top of a server. Even in some HPC or batch data analytics applications where you have to wait for hours for a certain result that is being computed in an enormous amount of memory, the cost savings of being able to survive a failing memory chip might be considerable.

One more thing: for those who need full control, the fact that every layer in the software stack is open makes the S822L very attractive. For now, the available "OpenCompute" Xeon servers that are also "open" seem to mostly density optimized servers and the openess seems limited on several levels. Rackspace felt that the current OpenCompute servers are not "open enough", and went for OpenPOWER servers instead. In all those markets, the S822L is very interesting alternative to the dual Xeon E5 servers.

Ultimately however, the performance-per-dollar Xeon E5 competitors will most likely be OpenPOWER third party servers. Those servers do not use CDIMMS, but regular RDIMMs. Other components such as disks, networkcards and PSUs will probably be cheaper but potentially also slightly less reliable.

All in all, the arrival of OpenPOWER servers is much more exciting than most of us anticipated. Although the IBM POWER8 servers can not beat the performance/watt ratio of the Xeon, we now have a server processor that is not only cheaper than Intel's best Xeons, but that can also keep up with them. Combine that with the fact that IBM has lined up POWER8+ for next year and a whole range of server vendors is building their own POWER8 based servers, and we have a lot to look forward to!

Energy and Pricing


View All Comments

  • JohanAnandtech - Saturday, November 7, 2015 - link

    suggestions on how to to do this? OpenSSL 1.02 will support the build in crypto accelerator, but I am not sure on how I would be able to see if the crypto code uses VMX. Reply
  • SarahKerrigan - Monday, November 9, 2015 - link

    Compile with -qreport in XL C/C++. Reply
  • Oxford Guy - Saturday, November 7, 2015 - link

    Typo on page 2:

    The resuls are that Google is supporting the efforts and Rackspace has even build their own OpenPOWER server called "Barreleye".
  • Ryan Smith - Saturday, November 7, 2015 - link

    Thanks. Reply
  • iwod - Saturday, November 7, 2015 - link

    In terms of 100, POWER Software Ecosystem manage to scale from 10 to 20, so that is a 100% increase but still very very low. Will we see POWER CPU / Server that is cheap enough to compete with Xeon E3 / E5, where most of the volume are? Compared to E7 is like comparing Server CPU for the 10% of the market.

    Intel will be moving to 14nm E7, I don't see anyone making POWER CPU at 14nm anytime soon.

    Intel DC business are growing, and it desperately need a competitor, such as POWER to combat E7 and AMD Zen from the bottom.
  • Frenetic Pony - Saturday, November 7, 2015 - link

    Nice review! It just confirms my question however of "What does IBM do?" Seriously, what do they do anymore? All I see are headlines for things that never come out as actual products. Their servers suck up too much power per watt, they don't have their own semi conductor foundries, their semi conductor research seems like a bunch of useless paper tiger stuff, their much vaunted AI is better at playing Jeapordy than seemingly any real world use.

    Countdown to complete IBM bankruptcy/spinoff/selloff is closer than ever.
  • ws3 - Saturday, November 7, 2015 - link

    Since the dawn of computing, IBM has been in the business of providing solutions, rather than merely hardware. When you buy IBM you pay a huge amount of money, and what you get for that is support, with some hardware thrown in.

    Obviously this only appeals to wealthy customers who don't have or don't want to have an internal support organization that can duplicate what IBM offers. It seems to me that the number of such customers is decreasing over time, but as long as the US government is around, IBM will have at least one customer.
  • xype - Sunday, November 8, 2015 - link

    They make 2-5 Billion dollars of profit per quarter. "Countdown to complete IBM bankruptcy/spinoff/selloff is closer than ever." my ass. Reply
  • PowerTrumps - Sunday, November 8, 2015 - link

    Pretty fair and even handed review; don't agree with it all and definitely feel there is room to learn and improve. Btw, full disclosure, I am a System Architect focusing on Power technology for a Business Partner.

    With regard to compilers I would suggest IBM's SDK for Linux on Power & Advanced Tool Chain (ATC) provide development tools and open source optimized dev stack (ie gcc) for POWER8. Details at: and

    MySQL is definitely relevant but with the new Linux distro's packaging MariaDB in place of MySQL I would have liked to see an Intel vs Power comparison with this MySQL alternative. MariaDB just announced v10.1 is delivering over 1M queries per second on POWER8.

    A commenter asked about Spark with POWER8. This blog discusses how it performs vs Intel.

    In addition to the commercial benchmarks often quoted such as SPEC, SAP and TPC like this SAP HANA result with SUSE on POWER8 ; SAP BW-EML (ie HANA) shows tremendous scaling with POWER8. many of the ISV's have produced their own. I have seen results for PostgreSQL, STAC ( Redis Labs, etc.

    Benchmarks are great, all vendors do them and most people realize you should take them with a grain of salt. One benefit of Power servers when using PowerVM, its native firmware based hypervisor is that it delivers tremendous compute efficiency to VM's. On paper things like TDP seem higher for Power vs Intel (especially E5_v3 chips) but when Power servers deliver consolidation ratio's with 2-4X (and greater) more VM's per core the TCA & TCO get real interesting. One person commented how SAP on Power would blow out a budget. It does just the opposite because how you can run in a Tier-2 architecture obtaining intra-server VM to VM efficiencies, compute efficiencies with fewer cores & servers which impacts everything in the datacenter. Add in increased reliability & serviceability features and you touch the servers less which means your business is running longer.

    And for more details on the open platform or those based on the OpenPOWER derivative using the "LC" designator such as S822LC in contrast to the S822L used as the focus in this article. and
  • JohanAnandtech - Sunday, November 8, 2015 - link

    Great feedback. We hope to get access to another POWER8(+) server and build further upon our existing knowledge. We have real world experience with Spark, so it is definitely on the list. The blog you linked seems to have used specific SPARK optimization for POWER, but the x86 reference system looks a bit "neglected". A real independent test would be very valuable there. The interesting part of Spark is that a good benchmark would be also very relevant for the real world as peak performance is one of the most important aspects of Spark, in contrast with databases where maximum performance is only a very small part of the experience.

    About MySQL, people have pointed out that the 5.7 version seems to scale a lot better, so that is together with MariaDB also on my "to test" list. Redis does not seem relevant for this kind of machine, it is single-threaded, almost impossible to test 160 instances.

    The virtualization part is indeed one of the most interesting parts, but it is a benchmarking nightmare. You got to keep response times at more or less the same levels while loading the machine with more and more VMs. We did that kind of testing until 2 years ago on x86, but it was very time consuming and we had a deep understanding on how vSphere worked. Building that kind of knowledge on PowerVM might be beyond our manpower and time :-).

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