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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JohanAnandtech - Thursday, July 21, 2016 - link
I don't think so, we just expressed it in ns so you can compare with IBM's numbers more easily. Can you elaborate why you think they are wrong?Taracta - Thursday, July 21, 2016 - link
Sorry, mixed up cycles with ns especially after reading the part about transition for the Intel from L3 to MEM.Sahrin - Thursday, July 21, 2016 - link
Yikes. Pictures without captions. Anandtech is terrible about this. ALWAYS caption your pictures, guys.djayjp - Thursday, July 21, 2016 - link
Are bar graphs not a thing anymore...?Drumsticks - Thursday, July 21, 2016 - link
Afaik, Anandtech has always used the chart when presenting things like SPEC. I'd guess it'd be for clutter reasons, but the exact reason is up to the editors to mention.JohanAnandtech - Thursday, July 21, 2016 - link
The reason for me is simply to give you the exact numbers and allow people to do their own comparisons.Drumsticks - Thursday, July 21, 2016 - link
Just to be clear, the Xeon CPU used today is 3 times more expensive than the Power8 CPU benchmarked? That's really impressive, isn't it? The Power8 has a pretty significant power increase, but if it's 43% faster, that cuts into the perf/w gap.I know we've only looked at SPEC so far in round 2, but this looks like a good showing for IBM. How big is the efficiency gap between 22nm SOI and 14nm FinFet? Any estimates?
Michael Bay - Thursday, July 21, 2016 - link
Selling at a loss is hardly impressive, especially in IBM`s case. This thing is literally their last chance.tipoo - Friday, July 22, 2016 - link
Is it at a loss, or is it just not at crazy Intel margins?Michael Bay - Saturday, July 23, 2016 - link
They`d have to have a healthy margin to offset all the R&D, plus IBM as a whole is not in a good financial position. Consider they sold their fab capability not so long ago.