The IBM POWER8 Review: Challenging the Intel Xeon
by Johan De Gelas on November 6, 2015 8:00 AM EST- Posted in
- IT Computing
- CPUs
- Enterprise
- Enterprise CPUs
- IBM
- POWER
- POWER8
Benchmark Configuration and Methodology
For our testing we installed 64-bit Ubuntu 15.04 Linux (Kernel version 3.19.0) so that we were able to use GCC 4.9.2, which has better support for the POWER8. We tried to keep the colors inside our benchmark graphs consistent: dark blue is IBM, light blue is the latest Intel Xeon generation (Haswell, E5 v3), and gray was reserved for older Intel systems.
Meanwhile on a quick aside, we should point out that IBM's servers also support PowerVM and KVM virtualization, however we decided not to make use of it to keep the complexity of the tests under control. As we explained in the introduction, porting and tuning the usual benchmarks was quite a challenge, and virtualization makes benchmarking a lot more complex. Testing virtualized workloads was thus beyond the scope of this article.
All tests have been done with the help of Kirth and Wannes of the Sizing Servers Lab.
IBM S822L (2U Chassis)
| CPU | Two IBM POWER8 3.425 GHz 10 cores |
| RAM | 128GB (8x16GB) IBM CDIMMs |
| Internal Disks | 2x 300GB 15K RPM SAS Disks (boot) 1x Intel DC P3700 400 GB (Data and benchmarks) |
| Motherboard | No idea |
| BIOS version | OPAL v3 |
| PSU | Dual Emerson 1400W |
Intel's Xeon E5 Server – "Wildcat Pass" (2U Chassis)
| CPU | Two Intel Xeon processor E5-2699 v3 (2.3GHz, 18c, 45MB L3, 145W) Two Intel Xeon processor E5-2695 v3 (2.3 GHz, 14c, 35MB L3, 120W) Two Intel Xeon processor E5-2667 v3 (3.2 GHz, 8c, 20MB L3, 135W) Two Intel Xeon processor E5-2650L v3 (1.8GHz, 12c, 30MB L3, 65W) |
| RAM | 128GB (8x16GB) Samsung M393A2G40DB0 (RDIMM) |
| Internal Disks | 2x Intel MLC SSD710 200GB (boot) 1x Intel DC P3700 400 GB (Data and benchmarks) |
| Motherboard | Intel S2600WTT |
| BIOS version | version 1.01 |
| PSU | Delta Electronics 750W DPS-750XB A (80+ Platinum) |
All C-states are enabled in both the BIOS.
Other Notes
Both servers are fed by a standard European 230V (16 Amps max.) powerline. The room temperature is monitored and kept at 23°C by our Airwell CRACs.
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FunBunny2 - Friday, November 6, 2015 - link
"The z10 processor was co-developed with and shares many design traits with the POWER6 processor, such as fabrication technology, logic design, execution unit, floating-point units, bus technology (GX bus) and pipeline design style, i.e., a high frequency, low latency, deep (14 stages in the z10), in-order pipeline." from the Wiki.Yes, the z continues the CISC ISA from the 360 (well, sort of) rather than hardware RISC, but as Intel (amongst others) has demonstrated, CISC ISA doesn't have to be in hardware. In fact, the 360/30 (lowest tier) was wholly emulated, as was admitted then. Today, we'd say "micro-instructions". All those billions of transistors could have been used to implement X86 in hardware, but Intel went with emulation, sorry micro-ops.
What matters is the underlying fab tech. That's not going anywhere.
FunBunny2 - Friday, November 6, 2015 - link
^^ should have gone to KevinG!!Kevin G - Saturday, November 7, 2015 - link
The GX bus in the mainframes was indeed shared by POWER chips as that enabled system level component sharing (think chipsets).However, attributes like the execution unit and the pipeline depth are different between the POWER6 and z10. At a bird's eye view, they do look similar but the implementation is genuinely different.
Other features like SMT were introduced with the POWER5 but only the most recent z13 chip has 2 way SMT. Features like out-of-order execution, SMT, SIMD were once considered too exotic to validate in the mainframe market that needed absolute certainty in its hardware states. However, recent zArch chips have implemented these features, sometimes decades after being introduced in POWER.
The other thing is that IBM has been attempting to get get more and more of the zArch instruction set to be executed by hardware and no microcode. Roughly 75% to 80% of instructions are handled by microcode (there is a bit of a range here as some are conditional to use microcode).
JohanAnandtech - Saturday, November 7, 2015 - link
I believe that benchmark uses about 8 threads and not very well either? Secondly, it is probably very well optimized for SSE/AVX. So you can imagine that the POWER8 will not be very good at it, unless we manually optimize it for Altivec/VSX. And that is beyond my skills :-)UrQuan3 - Monday, December 21, 2015 - link
I'm sure no one is still reading this as I'm posting over a month later, but...I tested handbrake/x264 on a bunch of cross-platform builds including Raspberry Pi 2. I found it would take 24 RPi2s to match a single i5-4670K. That was a gcc compiled handbrake on Raspbian vs the heavily optimized DL copy for Windows. Not too bad really. Also, x264 seems to scale fairly well with the number of cores. Still, POWER8 unoptimized would be interesting, though not a fair test.
BTW, I'd encourage you to use a more standard Linux version than 6-month experimental little-endian version of Ubuntu. The slides you show advertise support for Ubuntu 14.04 LTS, not 15.04. For something this new, you may need the latest, but that is often not the case.
stun - Friday, November 6, 2015 - link
@Johan You might want to fix "the platform" hyperlink at the bottom of page 4. It is invalid.JohanAnandtech - Friday, November 6, 2015 - link
Thanks and fixed.Ahkorishaan - Friday, November 6, 2015 - link
Couldn't read past the graphic on page 1. It's 2015 IBM, time to use a font that doesn't look like a toddler's handwriting.xype - Sunday, November 8, 2015 - link
To be fair, it seems that the slide is meant for management types… :PJtaylor1986 - Friday, November 6, 2015 - link
Using decimals instead of commas to denote thousands is jarring to your North American readers.