Sizing Up Servers: Intel's Skylake-SP Xeon versus AMD's EPYC 7000 - The Server CPU Battle of the Decade?
by Johan De Gelas & Ian Cutress on July 11, 2017 12:15 PM EST- Posted in
- CPUs
- AMD
- Intel
- Xeon
- Enterprise
- Skylake
- Zen
- Naples
- Skylake-SP
- EPYC
Single Threaded Integer Performance: SPEC CPU2006
Even in the server market where high core count CPUs are ruling the roost, high single threaded performance is still very desirable. It makes sure that a certain level of performance is guaranteed in every situation, not just in "throughput situations" of "embarrassingly parallel" software.
SPEC CPU2017 has finally launched, but it did so while our testing was already under way. So SPEC CPU2006 was still our best option to evaluate single threaded performance. Even though SPEC CPU2006 is more HPC and workstation oriented, it contains a good variety of integer workloads.
It is our conviction that we should try to mimic how performance critical software is compiled instead of trying to achieve the highest scores. To that end, we:
- use 64 bit gcc : by far the most used compiler on linux for integer workloads, good all round compiler that does not try to "break" benchmarks (libquantum...) or favor a certain architecture
- use gcc version 5.4: standard compiler with Ubuntu 16.04 LTS. (Note that this is upgraded from 4.8.4 used in earlier articles)
- use -Ofast -fno-strict-aliasing optimization: a good balance between performance and keeping things simple
- added "-std=gnu89" to the portability settings to resolve the issue that some tests will not compile with gcc 5.x
- run one copy of the test
The ultimate objective is to measure performance in non-"aggressively optimized" applications where for some reason – as is frequently the case – a "multi-thread unfriendly" task keeps us waiting.
First the single threaded results. It is important to note that thanks to modern turbo technology, all CPUs will run at higher clock speeds than their base clock speed.
- The Xeon E5-2690 ("Sandy Bridge") is capable of boosting up to 3.8 GHz
- The Xeon E5-2690 v3 ("Haswell") is capable of boosting up to 3.5GHz
- The Xeon E5-2699 v4 ("Broadwell") is capable of boosting up to 3.6 GHz
- The Xeon 8176 ("Skylake-SP") is capable of boosting up to 3.8 GHz
- The EPYC 7601 ("Naples") is capable of boosting up to 3.2 GHz
First we look at the absolute numbers.
| Subtest | Application type | Xeon E5-2690 @ 3.8 |
Xeon E5-2690 v3 @ 3.5 |
Xeon E5-2699 v4 @ 3.6 |
EPYC 7601 @3.2 |
Xeon 8176 @3.8 |
| 400.perlbench | Spam filter | 35 | 41.6 | 43.4 | 31.1 | 50.1 |
| 401.bzip2 | Compression | 24.5 | 24.0 | 23.9 | 24.0 | 27.1 |
| 403.gcc | Compiling | 33.8 | 35.5 | 23.7 | 35.1 | 24.5 |
| 429.mcf | Vehicle scheduling | 43.5 | 42.1 | 44.6 | 40.1 | 43.3 |
| 445.gobmk | Game AI | 27.9 | 27.8 | 28.7 | 24.3 | 31.0 |
| 456.hmmer | Protein seq. analyses | 26.5 | 28.0 | 32.3 | 27.9 | 35.4 |
| 458.sjeng | Chess | 28.9 | 31.0 | 33.0 | 23.8 | 33.6 |
| 462.libquantum | Quantum sim | 55.5 | 65.0 | 97.3 | 69.2 | 102 |
| 464.h264ref | Video encoding | 50.7 | 53.7 | 58.0 | 50.3 | 67.0 |
| 471.omnetpp | Network sim | 23.3 | 31.3 | 44.5 | 23.0 | 40.8 |
| 473.astar | Pathfinding | 25.3 | 25.1 | 26.1 | 19.5 | 27.4 |
| 483.xalancbmk | XML processing | 41.8 | 46.1 | 64.9 | 35.4 | 67.3 |
As raw SPEC scores can be a bit much to deal with in a dense table, we've also broken out our scores on a percentage basis. Sandy Bridge EP (Xeon E5 v1) is about 5 years old, the servers based upon this CPU are going to get replaced by newer ones. So we've made "Single threaded Sandy Bridge-EP performance" our reference (100%) , and compare the single threaded performance of all other architectures accordingly.
| Subtest | Application type | Xeon E5-2690 @ 3.8 |
Xeon E5-2690 v3 @ 3.5 |
Xeon E5-2699 v4 @ 3.6 | EPYC 7601 @3.2 | Xeon 8176 @ 3.8 |
| 400.perlbench | Spam filter | 100% | 119% | 124% | 89% | 143% |
| 401.bzip2 | Compression | 100% | 98% | 98% | 98% | 111% |
| 403.gcc | Compiling | 100% | 105% | 70% | 104% | 72% |
| 429.mcf | Vehicle scheduling | 100% | 97% | 103% | 92% | 100% |
| 445.gobmk | Game AI | 100% | 100% | 103% | 87% | 111% |
| 456.hmmer | Protein seq. analyses | 100% | 106% | 122% | 105% | 134% |
| 458.sjeng | Chess | 100% | 107% | 114% | 82% | 116% |
| 462.libquantum | Quantum sim | 100% | 117% | 175% | 125% | 184% |
| 464.h264ref | Video encoding | 100% | 106% | 114% | 99% | 132% |
| 471.omnetpp | Network sim | 100% | 134% | 191% | 99% | 175% |
| 473.astar | Pathfinding | 100% | 99% | 103% | 77% | 108% |
| 483.xalancbmk | XML processing | 100% | 110% | 155% | 85% | 161% |
SPEC CPU2006 analysis is complicated, and with only a few days spend on the EPYC server, we must admit that what follows is mostly educated guessing.
First off, let's gauge the IPC efficiency of the different architectures. Considering that the EPYC core runs at 12-16% lower clockspeeds (3.2 vs 3.6/3.8 GHz), getting 90+% of the performance of the Intel architectures can be considered a "strong" (IPC) showing for the AMD "Zen" architecture.
As for Intel's latest CPU, pay attention to the effect of the much larger L2-cache of the Skylake-SP core (Xeon 8176) compared to the previous generation "Broadwell". Especially perlbench, gobmk, hmmer and h264ref (the instruction part) benefit.
Meanwhile with the new GCC 5.4 compiler, Intel's performance on the "403.gcc benchmark" seems to have regressed their newer rchitectures. While we previously saw the Xeon E5-2699v4 perform at 83-95% of the "Sandy Bridge" Xeon E5-2690, this has further regressed to 70%. The AMD Zen core, on the other hand, does exceptionally well when running GCC. The mix of a high percentage of (easy to predict) branches in the instruction mix, a relatively small footprint, and a heavy reliance on low latency (mostly L1/L2/8 MB L3) seems to work well. The workloads where the impact of branch prediction is higher (somewhat higher percentage of branch misses) - gobmk, sjeng, hmmer - perform quite well on "Zen" too, which has a much lower branch misprediction penalty than AMD's previous generation architecture thanks to the µop cache.
Otherwise the pointer chasing benchmarks – XML procesing and Path finding – which need a large L3-cache, are the worst performing on EPYC.
Also notice the fact that the low IPC omnetpp ("network sim") runs slower on Skylake-SP than on Broadwell, but still much faster than AMD's EPYC. Omnetpp is an application that benefited from the massive 55 MB L3-cache of Broadwell, and that is why performance has declined on Skylake. Of course, this also means that the fractured 8x8 MB L3 of AMD's EPYC processor causes it to perform much slower than the latest Intel server CPUs. In the video encoding benchmark "h264ref" this plays a role too, but that benchmark relies much more on DRAM bandwidth. The fact that the EPYC core has higher DRAM bandwidth available makes sure that the AMD chip does not fall too far behind the latest Intel cores.
All in all, we think we can conclude that the single threaded performance of the "Zen architecture" is excellent, but it somewhat let down by the lower turbo clock and the "smaller" 8x8 MB L3-cache.
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Shankar1962 - Thursday, July 13, 2017 - link
So you think Intel won't release anything new again by then? Intel would be ready for cascadelake by then. None of the big players won't switch to AMD. Skylake alone is enough to beat epyc handsomely and cascadelake will just blow epyc. Its funny people are looking at lab results when real workloads are showing 1.5-1.7x speed improvementPixyMisa - Saturday, July 15, 2017 - link
This IS comparing AMD to Intel's newest CPUs, you idiot. Skylake loses to Epyc outright on many workloads, and is destroyed by Epyc on TCO.Shankar1962 - Sunday, July 16, 2017 - link
Mind your language assholeEither continue the debate or find another place for your shit and ur language
Real workloads don't happen in the labs you moron
Real workloads are specific to each company and Intel is ahead either way
If you have the guts come out with Q3 Q4 2017 and 2018 revenues from AMD
If you come back debating epyc won over skylake if AMD gets 5-10% share then i pity your common sense and your analysis
You are a bigger idiot because you spoiled a healthy thread where people were taking sides by presenting technical perspective
PixyMisa - Tuesday, July 25, 2017 - link
I'm sorry you're an idiot.Shankar1962 - Thursday, July 13, 2017 - link
Does not matter. We can debate this forever but Intel is just ahead and better optimized for real world workloads. Nvidia i agree is a potential threat and ahead in AI workloads which is the future but AMD is just an unnecessary hype. Since the fan boys are so excited with lab results (funny) lets look at Q3,Q4 results to see how many are ordering to test it for future deployment.martinpw - Wednesday, July 12, 2017 - link
I'm curious about the clock speed reduction with AVX-512. If code makes use of these instructions and gets a speedup, will all other code slow down due to lower overall clock speeds? In other words, how much AVX-512 do you have to use before things start clocking down? It feels like it might be a risk that AVX-512 may actually be counterproductive if not used heavily.msroadkill612 - Wednesday, July 12, 2017 - link
(sorry if a repost)Well yeah, but this is where it starts getting weird - 4-6 vega gpuS, hbm2 ram & huge raid nvme , all on the second socket of your 32 core, c/gpu compute ~Epyc server:
https://marketrealist.imgix.net/uploads/2017/07/A1...
from
http://marketrealist.com/2017/07/how-amd-plans-to-...
All these fabric linked processors, can interact independently of the system bus. Most data seems to get point to point in 2 hops, at about 40GBps bi-directional (~40 pcie3 lanes, which would need many hops), and can be combined to 160GBps - as i recall.
Suitably custom hot rodded for fabric rather than pcie3, the nvme quad arrays could reach 16MBps sequential imo on epycs/vegaS native nvme ports.
To the extent that gpuS are increasing their role in big servers, intel and nvidea simply have no answer to amd in the bulk of this market segment.
davide445 - Wednesday, July 12, 2017 - link
Finally real competition in the HPC market. Waiting for the next top500 AMD powered supercomputer.Shankar1962 - Wednesday, July 12, 2017 - link
Intel makes $60billion a year and its official that Skylake was shipping from Feb17 so i do not understand this excitement from AMD fan boys......if it is so good can we discuss the quarterly revenues between these companies? Why is AMD selling for very low prices when you claim superior performance over Intel? You can charge less but almost 40-50% cheap compared to Intel really?AMD exists because they are always inferior and can beat Intel only by selling for low prices and that too for what gaining 5-10% market which is just a matter of time before Intel releases more SKUs to grab it back
What about the software optimizations and extra BOM if someone switches to AMD?
What if AMD goes into hibernation like they did in last 5-6years?
Can you mention one innovation from AMD that changed the world?
Intel is a leader and all the technology we enjoy today happenned because of Intel technology.
Intel is a data center giant have head start have the resources money acquisitions like altera mobileeye movidus infineon nirvana etc and its just impossible that they will lose
Even if all the competent combines Intel will maintain atleast 80% share even 10years from now
Shankar1962 - Wednesday, July 12, 2017 - link
To add onNo one cares about these lab tests. Let's talk about the real world work loads.
Look at what Google AWS ATT etc has to say as they already switched to xeon sky lake
We should not really be debating if we have the clarity that we are talking about AMD getting just 5% -10% share by selling high end products they have for cheap prices....they fo not make too much money by doing that.....they have no other option as thats the only way they can dream of a 5-10% market share
For Analogy think Intel in semiconductor as Apple in selling smartphones
Intel has gross margins of ~63%
They have a solid product portfolio technologies and roadmap .....we can debate this forever but the revenues profits innovations and history between these companies can answer everything