Assessing IBM's POWER8, Part 1: A Low Level Look at Little Endian
by Johan De Gelas on July 21, 2016 8:45 AM ESTSingle-Threaded Integer Performance: SPEC CPU2006
Even though SPEC CPU2006 is more HPC and workstation oriented, it contains a good variety of integer workloads. Running SPEC CPU2006 is a good way to evaluate single threaded (or core) performance. The main problem is that the results submitted are "overengineered" and it is very hard to make any fair comparisons.
For that reason, we wanted to keep the settings as "real world" as possible. So we used:
- 64 bit gcc 5.2.1: most used compiler on Linux, good all round compiler that does not try to "break" benchmarks (libquantum...)
- -Ofast: compiler optimization that many developers may use
- -fno-strict-aliasing: necessary to compile some of the subtests
- base run: every subtest is compiled in the same way.
The ultimate objective is to measure performance in applications where for some reason – as is frequently the case – a "multi-thread unfriendly" task keeps us waiting.
Here is the raw data. Perlbench failed to compile on Ubuntu 15.10, so we skipped it. Still we are proud to present you the very first SPEC CPU2006 benchmarks on Little Endian POWER8.
On the IBM server, numactl was used to physically bind the 2, 4, or 8 copies of SPEC CPU to the first 2, 4, or 8 threads of the first core. On the Intel server, the 2 copy benchmark was bound to the first core.
| Subtest SPEC CPU2006 Integer |
Application Type |
IBM POWER8 10c@3.5 Single Thread |
IBM POWER8 10c@3.5 SMT-2 |
IBM POWER8 10c@3.5 SMT-4 |
IBM POWER8 10c@3.5 SMT-8 |
Xeon E5-2699 v4 2.2-3.6 |
Xeon E5-2699 v4 2.2-3.6 (+HT) |
| 400.perlbench | Spam filter | N/A | N/A | N/A | N/A | 32.2 | 36.6 |
| 401.bzip2 | Compress | 17.5 | 26.9 | 33.7 | 35.2 | 19.2 | 25.3 |
| 403.gcc | Compiling | 32.1 | 44.6 | 56.6 | 61.5 | 28.9 | 33.3 |
| 429.mcf | Vehicle scheduling | 47.1 | 50 | 64.1 | 73.5 | 39 | 43.9 |
| 445.gobmk | Game AI | 20.2 | 31.3 | 41.4 | 43.1 | 22.4 | 27.7 |
| 456.hmmer | Protein seq. analyses | 19.1 | 27.1 | 28.6 | 22.5 | 24.2 | 28.4 |
| 458.sjeng | Chess | 17.1 | 25.4 | 32.6 | 33.1 | 24.8 | 28.3 |
| 462.libquantum | Quantum sim |
44.7 | 82.1 | 109 | 108 | 59.2 | 67.3 |
| 464.h264ref | Video encoding | 32.7 | 45.4 | 53.3 | 48.8 | 40.7 | 40.7 |
| 471.omnetpp | Network sim |
23.5 | 29.1 | 37.1 | 42.5 | 23.5 | 29.9 |
| 473.astar | Pathfinding | 16.5 | 24.8 | 33.5 | 36.9 | 18.9 | 23.6 |
| 483.xalancbmk | XML processing | 24.9 | 35.3 | 44.7 | 48.4 | 35.4 | 41.8 |
First we look at how well SMT-2, SMT-4 and SMT-8 work on the IBM POWER8.
| Subtest SPEC CPU2006 Integer |
Application Type |
IBM POWER8 10c@3.5 Single Thread |
IBM POWER8 10c@3.5 SMT-2 |
IBM POWER8 10c@3.5 SMT-4 |
IBM POWER8 10c@3.5 SMT-8 |
| 400.perlbench | Spam filter | N/A | N/A | N/A | N/A |
| 401.bzip2 | Compress | 100% | 154% | 193% | 201% |
| 403.gcc | Compiling | 100% | 139% | 176% | 192% |
| 429.mcf | Vehicle scheduling | 100% | 106% | 136% | 156% |
| 445.gobmk | Game AI | 100% | 155% | 205% | 213% |
| 456.hmmer | Protein seq. analyses | 100% | 142% | 150% | 118% |
| 458.sjeng | Chess | 100% | 149% | 191% | 194% |
| 462.libquantum | Quantum sim |
100% | 184% | 244% | 242% |
| 464.h264ref | Video encoding | 100% | 139% | 163% | 149% |
| 471.omnetpp | Network sim |
100% | 124% | 158% | 180% |
| 473.astar | Pathfinding | 100% | 150% | 203% | 224% |
| 483.xalancbmk | XML processing | 100% | 142% | 180% | 194% |
The performance gains from single threaded operation to two threads are very impressive, as expected. While Intel's SMT-2 offers in most subtests between 10 and 25% better performance, the dual threaded mode of the POWER8 boosts performance by 40 to 50% in most applications, or more than twice as much relative to the Xeons. Not one benchmark regresses when we throw 4 threads upon the IBM POWER8 core. The benchmarks with high IPC such as hmmer peak at SMT-4, but most subtests gain a few % when running 8 threads.
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DomOfSF - Thursday, July 21, 2016 - link
Johan de Gelas: blowing minds and educating "the rest of us" since...I dunno, a really long time ago (especially in internet years). Great job on the data, but the real good stuff is in your thoughts and analysis. Thank you!close - Saturday, July 23, 2016 - link
Over a decade...JohanAnandtech - Thursday, July 28, 2016 - link
13 years in the server business, 18 years now of reviewing hardware :-). Thx !!jamyryals - Thursday, July 21, 2016 - link
It seems to me, Intel's focus on bringing their CPU architecture design all the way down to 5W is the reason IBM is able to stand out against them. Intel is focused on creating a scalable architecture while IBM can throw the whole kitchen sink at the server market.Fascinating article, I really enjoyed it.
smilingcrow - Thursday, July 21, 2016 - link
Intel has plenty of unique features in their server platforms which aren't in the consumer platforms so I don't think that is the issue.jospoortvliet - Tuesday, July 26, 2016 - link
The basic design of the core still is the same so there is probably at least some truth in the statement of Jamy.Kevin G - Wednesday, July 27, 2016 - link
Up until this point. Consumer SkyLake and server SkyLake are going to be two different designs. They're certainly related but server SkyLake will have 512 KB of L2 cache per core and support AVX-512 instructions.Server SkyLake is also going to support 3D Xpoint DIMMs, though that difference is more with the platform/chipset than the actual CPU core.
floobit - Thursday, July 21, 2016 - link
Very interesting. It seems odd to me that they chose to configure it in a 2U - except for big data clusters, most of the market space I see this playing is dominated by FC to a SAN. Is this a play in the big data cluster space, or the more traditional AIX/DB2/big iron that IBM has owned for so long?Some questions I'd have:
what virtualization is possible with this architecture? presumably just the standard PowerVM? How well does that work?
What is the impact of IO latency? Could you throw a P3700 or two in here?
JohanAnandtech - Thursday, July 21, 2016 - link
2U: Besides big data storage needs, I suspect 2U is necessary for adequate cooling for the POWER8 chip.Virtualization: Linux KVM works well as far as I know.
We actually tried out a P3700 in there (see: http://www.anandtech.com/show/9567/the-power-8-rev... ) and it worked very well. I asked IBM what a customer should expect when using third party storage (probably no support, but how about waranty?) but no answer yet.
mystic-pokemon - Friday, July 22, 2016 - link
Hi Johan2U is not necessary for cooling a POWER 8 Chip. We do that better with our Barreleye (1.25 OU design). Even storage wise Barreleye has 15 Disk storage bay that can be seen in below links.
http://www.v3.co.uk/v3-uk/news/2453992/google-and-...
Let me know if you wanna ever benchmark a Barreleye. What specific POWER8 proc are you benchmarking with ? (Turismo?). I believe it does slightly better than S812LC on many benchmarks based on the variant of power8 proc S812LC runs.