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
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This morning kicks off a very interesting time in the world of server-grade CPUs. Officially launching today is Intel's latest generation of Xeon processors, based on the "Skylake-SP" architecture. The heart of Intel's new Xeon Scalable Processor family, the "Purley" 100-series processors incorporate all of Intel's latest CPU and network fabric technology, not to mention a very large number of cores.
Meanwhile, a couple of weeks back AMD soft-launched their new EPYC 7000 series processors. Based on the company's Zen architecture and scaled up to server-grade I/O and core counts, EPYC represents an epic achievement for AMD, once again putting them into the running for competitive, high performance server CPUs after nearly half a decade gone. EPYC processors have begun shipping, and just in time for today's Xeon launch, we also have EPYC hardware in the lab to test.
Today's launch is a situation that neither company has been in for quite a while. Intel hasn't had serious competition in years, and AMD has't been able to compete. As a result, both companies are taking the other's actions very seriously.
In fact we could go on for much longer than our quip above in describing the rising tension at the headquarters of AMD and Intel. For the first time in 6 years (!), a credible alternative is available for the newly launched Xeon. Indeed, the new Xeon "Skylake-SP" is launching today, and the yardstick for it is not the previous Xeon (E5 version 4), but rather AMD's spanking new EPYC server CPU. Both CPUs are without a doubt very different: micro architecture, ISA extentions, memory subsystem, node topology... you name it. The end result is that once again we have the thrilling task of finding out how the processors compare and which applications their various trade-offs make sense.
The only similarity is that both server packages are huge. Above you see the two new Xeon packages –with and without an Omni-Path connector – both of which are as big as a keycard. And below you can see how one EPYC CPU fills the hand of AMD's CEO Dr. Lisa Su.
Both are 64 bit x86 CPUs, but that is where the similarities end. For those of you who have been reading Ian's articles closely, this is no surprise. The consumer-focused Skylake-X is the little brother of the newly launched Xeon "Purley", both of which are cut from the same cloth that is the Skylake-SP family. In a nutshell, the Skylake-SP family introduces the following new features:
- AVX-512 (Many different variants of the ISA extension are available)
- A 1 MB (instead of a 256 KB) L2-cache with a non-inclusive L3
- A mesh topology to connected the cores and L3-cache chunks together
Meanwhile AMD's latest EPYC Server CPU was launched a few weeks ago:
On the package are four silicon dies, each one containing the same 8-core silicon we saw in the AMD Ryzen processors. Each silicon die has two core complexes, each of four cores, and supports two memory channels, giving a total maximum of 32 cores and 8 memory channels on an EPYC processor. The dies are connected by AMD’s newest interconnect, the Infinity Fabric...
In the next pages, we will be discussing the impact of these architectural choices on server software.
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TheOriginalTyan - Tuesday, July 11, 2017 - linkAnother nicely written article. This is going to be a very interesting next couple of months.
coder543 - Tuesday, July 11, 2017 - linkI'm curious about the database benchmarks. It sounds like the database is tiny enough to fit into L3? That seems like a... poor benchmark. Real world databases are gigabytes _at best_, and AMD's higher DRAM bandwidth would likely play to their favor in that scenario. It would be interesting to see different sizes of transactional databases tested, as well as some NoSQL databases.
psychobriggsy - Tuesday, July 11, 2017 - linkI wrote stuff about the active part of a larger database, but someone's put a terrible spam blocker on the comments system.
Regardless, if you're buying 64C systems to run a DB on, you likely will have a dataset larger than L3, likely using a lot of the actual RAM in the system.
roybotnik - Wednesday, July 12, 2017 - linkYea... we use about 120GB of RAM on the production DB that runs our primary user-facing app. The benchmark here is useless.
haplo602 - Thursday, July 13, 2017 - linkI do hope they elaborate on the DB benchmarks a bit more or do a separate article on it. Since this is a CPU article, I can see the point of using a small DB to fit into the cache, however that is useless as an actual DB test. It's more an int/IO test.
I'd love to see a larger DB tested that can fit into the DRAM but is larger than available caches (32GB maybe ?).
ddriver - Tuesday, July 11, 2017 - linkWe don't care about real world workloads here. We care about making intel look good. Well... at this point it is pretty much damage control. So let's lie to people that intel is at least better in one thing.
Let me guess, the databse size was carefully chosen to NOT fit in a ryzen module's cache, but small enough to fit in intel's monolithic die cache?
Brought to you by the self proclaimed "Most Trusted in Tech Since 1997" LOL
Ian Cutress - Tuesday, July 11, 2017 - linkI'm getting tweets saying this is a severely pro AMD piece. You are saying it's anti-AMD. ¯\_(ツ)_/¯
ddriver - Tuesday, July 11, 2017 - linkWell, it is hard to please intel fanboys regardless of how much bias you give intel, considering the numbers.
I did not see you deny my guess on the database size, so presumably it is correct then?
ddriver - Tuesday, July 11, 2017 - linkIn the multicore 464.h264ref test we have 2670 vs 2680 for the xeon and epyc respectively. Considering that the epyc score is mathematically higher, howdoes it yield a negative zero?
Granted, the difference is a mere 0.3% advantage for epyc, but it is still a positive number.
Headley - Friday, July 14, 2017 - linkI thought the exact same thing