The Intel Xeon E7-8800 v3 Review: The POWER8 Killer?
by Johan De Gelas on May 8, 2015 8:00 AM EST- Posted in
- CPUs
- IT Computing
- Intel
- Xeon
- Haswell
- Enterprise
- server
- Enterprise CPUs
- POWER
- POWER8
Single-threaded Integer Performance: 7-Zip
The profile of a compression algorithm is somewhat similar to many server workloads: it can be hard to extract instruction level parallelism (ILP) and it's sensitive to memory parallelism and latency. The instruction mix is a bit different, but it's still somewhat similar to many server workloads. Testing single threaded is also a great way to check how well the turbo boost feature works in a CPU.
And as one more reason to test performance in this manner, the 7-zip source code is available under the GNU LGPL license. That allows us to recompile the source code on every machine with the -O2 optimization with gcc 4.8.2.
We added the 7-zip scores that we could find at the 7-zip benchmark page. But there is more. The numbers on the 7-zip bench page have no software details, so we could not be sure that they would be accurate. So we managed to get a brief session on a POWER8 "for development purposes" server. The hardware specs can be read below:
Yes, we only got access to 1 core (8 threads) and 2 GB of RAM. So real world server benchmarking was out of the question. Nevertheless, it's a start. To that end we tested with gcc 4.9.1 (supports POWER8) and recompiled our source with the "-O2 -mtune="power8" options on Ubuntu Linux 14.10 for POWER.
Let us first focus on the new Haswell core inside the Xeon E7, which offers a solid 10% improvement. Turbo boost brings the clockspeed of the Haswell core close enough to the Ivy Bridge core (3.3GHz vs 3.4GHz) and the improved core does the rest. Nevertheless, it is clear that we should not expect huge performance increases with a 10% faster core and 20% more cores.
Back to the more exciting stuff: the fight between Intel and IBM, between the Xeon "Haswell" and the POWER8 chip. The Haswell core is a lot more sophisticated: single threaded performance at 3.3 GHz (turbo) is no less than 50% higher than the POWER8 at 3.4 GHz. That means that the Haswell core is a lot more capable when it comes to extracting ILP out of that complex code.
However, when the IBM monster is allowed to use 8 simultaneous threads spread out over one core, something magical happens. Something that we have not seen in a long, long time: the Intel chip is no longer on top. When you use all the available threading resources in one core, the 3.4 GHz chip is a tiny bit (2%) faster than the best Intel Xeon at 3.3 GHz.
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DanNeely - Friday, May 8, 2015 - link
Intel's 94% market share is still only ~184k systems. That's tiny compared to the mainstream x86 market; and doesn't give a lot of (budgetary) room to make radical changes to CPU vs just scaling shared designs to a huger layout.theeldest - Friday, May 8, 2015 - link
184k for 4S systems. The number of 2S systems *greatly* outnumbers the 184k.Samus - Sunday, May 10, 2015 - link
by 100 orders of magnitude, easily.2S systems are everywhere these days, I picked up a Lenovo 2S Xeon system for $600 NEW (driveless, 4GB RAM) from CDW.
4S, on the other hand, is considerably more rare and starts at many thousands, even with 1 CPU included.
erple2 - Sunday, May 10, 2015 - link
Well, maybe 2 orders of magnitude. 100 orders of magnitude would imply, based on the 184k 4S systems, more 2S systems than atoms in the universe. Ok, I made that up, I don't know how many atoms are in the universe, but 10^100 is a really big number. Well, 10^105, if we assume 184k 4S systems.I think you meant 2 orders of magnitude.
mapesdhs - Sunday, May 10, 2015 - link
Yeah, that made me smile too, but we know what he meant. ;)evolucion8 - Monday, May 11, 2015 - link
That would be right if Intel cores are wide enough which aren't compared to IBM. For example, according to this review, enabling two way SMT boosted the performace to 45% and adding two more threads added 30% more performance. On the other hand, enabling two way SMT on the latest i7 architecture can only go up to 30% on the best case scenario.chris471 - Friday, May 8, 2015 - link
Great article, and I'm looking forward to see more Power systems.I would have loved to see additional benchmarks with gcc flags -march=native -Ofast. Should not change stream triad results, but I think 7zip might profit more on Power than on Xeon. Most software is not affected by the implied -ffast-math.
close - Friday, May 8, 2015 - link
It reminds me of the time when Apple gave up on PowerPC in mobiles because the new G5s were absolute power guzzlers and made space heaters jealous. And then gave up completely and switched to Intel because the 2 dual core PowerPC 970MP CPUs at 2.5GHz managed to pull 250W of power and needed liquid cooling to be manageable.IBM is learning nothing from past mistakes. They couldn't adapt to what the market wanted and the more nimble competition was delivering 25-30 years ago when fighting Microsoft, it already lost business to Intel (which is actually only nimble by comparison), and it's still doing business and building hardware like we're back in the '70s mainframe age.
name99 - Friday, May 8, 2015 - link
You are assuming that the markets IBM sells into care about the things you appear to care about (in particular CPU performance per watt). This is a VERY dubious assumption.The HPC users MAY care (but I'd need to see evidence of that). For the business users, the cost of the software running on these systems dwarfs the lifetime cost of their electricity.
SuperVeloce - Saturday, May 9, 2015 - link
They surely care. Why wouldn't they. A whole server rack or many of them in fact do use quite a bit of power. And cooling the server room is very expensive.