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
AMD’s EPYC 7000-Series Processors
As announced back at the official launch, AMD is planning to hit both the dual socket and single socket markets. With up to 32 cores, 64 threads, 2TB/socket support and 128 PCIe lanes per CPU, they believe that by offering a range of core counts and frequencies, they have the nous to attack Intel, even if it comes at a slight IPC disadvantage.
AMD’s main focus will be on the 2P parts, where each CPU will use 64 PCIe lanes (using the Infinity Fabric protocol) to connect to each other, meaning that in a 2P system there will still be 128 PCIe 3.0 lanes to go around for add-in devices. There will be the top four SKUs available initially, and the other parts should be in the hands of OEMs by the end of July. All the CPUs will have access to all 64MB of the L3 cache, except the 7200-series which will have access to half.
The new processors from AMD are called the EPYC 7000 series, with names such as EPYC 7301 and EPYC 7551P. The naming of the CPUs is as follows:
EPYC 7551P
- EPYC = Brand
- 7 = 7000 Series
- 30/55 = Dual Digit Number indicative of stack positioning / performance (non-linear)
- 1 = Generation
- P = Single Socket, not present in Dual Socket
So in the future, we will see second generation ‘EPYC 7302’ processors, or if AMD scales out the design there may be EPYC 5000 processors with fewer silicon dies inside, or EPYC 3000 with a single die but for the EPYC platform socket (obviously, those last two are speculation).
But starting with the 2P processors:
| AMD EPYC Processors (2P) | |||||||||
| Cores Threads |
Frequency (GHz) | L3 | DRAM | PCIe | TDP | Price | |||
| Base | All | Max | |||||||
| EPYC 7601 | 32 / 64 | 2.20 | 2.70 | 3.2 | 64 MB | 8-Ch DDR4 2666 MT/s |
8 x16 128 PCIe |
180W | $4200 |
| EPYC 7551 | 32 / 64 | 2.00 | 2.55 | 3.0 | 180W | >$3400 | |||
| EPYC 7501 | 32 / 64 | 2.00 | 2.60 | 3.0 | 155W/170W | $3400 | |||
| EPYC 7451 | 24 / 48 | 2.30 | 2.90 | 3.2 | 180W | >$2400 | |||
| EPYC 7401 | 24 / 48 | 2.00 | 2.80 | 3.0 | 155W/170W | $1850 | |||
| EPYC 7351 | 16 / 32 | 2.40 | 2.9 | 155W/170W | >$1100 | ||||
| EPYC 7301 | 16 / 32 | 2.20 | 2.7 | 155W/170W | >$800 | ||||
| EPYC 7281 | 16 / 32 | 2.10 | 2.7 | 32 MB | 155W/170W | $650 | |||
| EPYC 7251 | 8 / 16 | 2.10 | 2.9 | 120W | $475 | ||||
The top part is the EPYC 7601, which is the CPU we were provided for in this comparison. This is a 32-core part with simultaneous multithreading, a TDP of 180W and a tray price of $4200. As the halo part, it also gets the good choice on frequencies: 2.20 GHz base, 3.2 GHz at max turbo (up to 12 cores active) and 2.70 GHz when all cores are active.
Moving down the stack, AMD will offer 24, 16 and 8-core parts. These will disable 1, 2 and 3 cores per CCX respectively, as we saw with the consumer Ryzen processors, and is done in order to keep core-to-core latencies more predictable (as well as keeping access to all the L3 cache). What is interesting to note is that AMD will offer a 32-core part at 155W (when using DDR4-2400) for $3400, which is expected to be very competitive compared to Intel (and support 2.66x more DRAM per CPU).
The 16-core EPYC 7281, while having half the L3, will be available for $650, making an interesting 2P option. Even the bottom processor at the stack, the 8-core EPYC 7251, will support the full 2TB of DRAM per socket as well as 128 PCIe lanes, making it a more memory focused SKU and having almost zero competition on these sorts of builds from Intel. For software that requires a lot of memory but pays license fees per core/socket, this is a nice part.
For single socket systems, AMD will offer the following three processors:
| AMD EPYC Processors (1P) | |||||||||
| Cores Threads |
Frequency (GHz) | L3 | DRAM | PCIe | TDP | Price | |||
| Base | All | Max | |||||||
| EPYC 7551P | 32 / 64 | 2.0 | 2.6 | 3.0 | 64 MB | 8-Ch DDR4 2666 MT/s |
8 x16 128 PCIe |
180W | $2100 |
| EPYC 7401P | 24 / 48 | 2.0 | 2.8 | 3.0 | 155W/170W | $1075 | |||
| EPYC 7351P | 16 / 32 | 2.4 | 2.9 | 155W/170W | $750 | ||||
These processors mirror the specifications of the 2P counterparts, but have a P in the name and slightly different pricing.
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tamalero - Tuesday, July 11, 2017 - link
How is that different if AMD ran stuff that is extremely optimized for them?Friendly0Fire - Tuesday, July 11, 2017 - link
That's kinda the point? You want to benchmark the CPUs in optimal scenarios, since that's what you'd be looking at in practice. If one CPU's weakness is eliminated by using a more recent/tweaked compiler, then it's not a weakness.coder543 - Tuesday, July 11, 2017 - link
Rather, you want to test under practical scenarios. Very few people are going to be running 17.04 on production grade servers, they will run an LTS release, which in this case is 16.04.It would be good to have benchmarks from 17.04 as another point of comparison, but given how many things they didn't have time to do just using 16.04, I can understand why they didn't use 17.04.
Santoval - Wednesday, July 12, 2017 - link
A compromise can be found by upgrading Ubuntu 16.04's outdated kernel. Ubuntu LTS releases include support for rolling HWE Stacks, which is a simple meta package for installing newer kernels compiled, modified, tested and packaged by the Ubuntu Kernel Team, and installed directly from the official Ubuntu repositories (not via a Launchpad PPA). With HWE 16.04 LTS can install up to the kernel of 18.04 LTS.I also use 16.04 LTS + HWE (it just requires installing the linux-generic-hwe-16.04 package), which currently provides the 4.8 kernel. There is even a "beta" version of HWE (the same package plus an -edge at the end) for installing the 4.10 kernel (aka the kernel of 17.04) earlier, which will normally be released next month.
I just spotted various 4.10 kernel listings after checking in Synaptic, so they must have been added very recently. After that there are two more scheduled kernel upgrades, as is shown in the following link. Of course HWE upgrades solely the kernel, it does not upgrade any application or any of the user level parts to a more recent version of Ubuntu.
https://wiki.ubuntu.com/Kernel/RollingLTSEnablemen...
CajunArson - Tuesday, July 11, 2017 - link
Considering the similarities between RyZen and Haswell (that aren't coincidental at all) you are already seeing a highly optimized set of RyZen results.But I have no problem seeing RyZen be tested with the newest distros, the only difference being that even Ubuntu 16.04 already has most of the optimizations for RyZen baked in.
coder543 - Tuesday, July 11, 2017 - link
What similarities? They're extremely different architectures. I can't think of any obvious similarities. Between the CCX model, caches being totally different layouts, the infinity fabric, Intel having better AVX-256/512 stuff (IIRC), etc.I don't think 16.04 is naturally any more optimized for Ryzen than it is for Skylake-SP.
CajunArson - Tuesday, July 11, 2017 - link
Oh please, at the core level RyZen is a blatant copy-n-paste of Haswell with the only exception being they just omitted half the AVX hardware to make their lives easier.It's so obvious that if you followed any of the developer threads for people optimizing for RyZen they say to just use the Haswell compiler optimizations that actually work better than the official RyZen optimization flags.
ddriver - Tuesday, July 11, 2017 - link
Can't tell if this post is funny or sad.CajunArson - Tuesday, July 11, 2017 - link
It's neither: It's accurate.Don't believe me? Look at the differences in performance of the holy 1800X over multiple Linux distros ranging from pretty new (OpenSuse Tumbleweed) to pretty old (Fedora 23 from 2015): http://www.phoronix.com/scan.php?page=article&...
Nowhere near the variation that we see with Skylake X since Haswell was already a solved problem long before RyZen lauched.
coder543 - Tuesday, July 11, 2017 - link
Right, of course. Ryzen is a copy-and-paste of Haswell.Don't make me laugh.