We wanted to discuss our test configuration before moving on to our performance numbers.
AMD EPYC 3251 Test Configuration
Our test configuration was the AMD Wallaby platform. Since this is an embedded SoC, the CPU is affixed to the motherboard.
- Motherboard: AMD Wallaby
- CPU: AMD EPYC 3251
- RAM: 2x 16GB DDR4-2400 RDIMMs (Samsung), 2x 16GB DDR4-2666 RDIMMs (Samsung), 2x 32GB DDR4-2400 RDIMMs (Micron), 2x 32GB DDR4-2400 RDIMMs (SK.Hynix)
- GPU: AMD FirePro W2100
- SSD: Intel DC S3710 400GB
- OS SSD: Samsung 850 Pro 256GB SATA 2.5″
There are a few major caveats that we wanted to point out using a platform like this.
First off, the vast majority of embedded platforms that we test have IPMI interfaces. That usually means an Arm-based ASPEED AST2500 series BMC these days (AST2400 series previously.) That chip is accompanied by a single DRAM package. It also is usually wired to an Ethernet LAN port and provides some graphics capability. All of this adds additional power consumption to the tune of several watts. That is a big deal in the embedded space when power is usually under 100W at the wall. Our system had an AMD FirePro W2100 GPU in the PCIe x16 slot. That GPU sits mostly idle during our testing, but it adds to the power figures and is rated for <26W power consumption which is huge in an embedded platform.
Generally, we use SATA DOMs for OS drives as that is incredibly common in the embedded market. The Wallaby platform did not have SATA DOM power that we could find so we ended up using a Samsung 2.5″ SSD. This is a departure from our standard testing procedure.
We tried several DACs with the Wallaby platform but ended up using short-range optics instead. Typically, our embedded reviews use DACs connected to SFP+ ports. In this test platform, we needed to use recommended optics. With development platforms, one often needs to use specific I/O hardware. We saw this in our early Intel Xeon D-1500 work as was noted in Intel Xeon D-1540 and SFP+ 10GbE Microserver X552 NIC where the Intel development platform even required a specific powered USB hub. We had to make a concession on our standard setup which was necessary.
This is a decent system with 32GB of RAM. We tried 64GB of RAM in 2x 32GB RDIMM configurations successfully. We would have tried 128GB in 4x 32GB but we were limited by the physical platform.
Finally, we performed testing with both a more production firmware as well as a “debug” firmware. Getting reliable data meant that we had to calibrate the two sets of results since we had more control over the debug firmware. We saw deltas in the 2-3% range. That meant that the differences were easy to spot, but they were there. As a result of what we are seeing with firmware updates, we think that this may be a case like the EPYC 7000 series where future firmware updates will get additional performance from the platform.
Deciding to Proceed
With all of these caveats, we still decided to proceed with publishing our review for a simple reason. The embedded server CPU/ control plane market is still largely an Intel domain with the Intel Xeon D-1500, D-2100 and Atom C3000 series. Arm-based servers are starting to show more performance. If you have x86 code, and want to run it on non-Intel hardware to give your supply chain diversification, then the market needs AMD EPYC 3000. Our role in the market for years has been to stay on the bleeding edge of these embedded CPUs so we wanted to get our readers information.
Our goal with this piece is to help our readers understand a relative performance ranking between CPUs. That way if you see two options from a sales rep quote, you have some idea of what you are getting with each option. The market needs this data if there is going to be an x86 competitor to the Intel Xeon D monopoly in the space. We wanted to get data out into the community in an attempt to get more designs built and options for customers.
AMD EPYC 3251 Wallaby Platform Topology
Unlike the larger AMD EPYC 7000 series, the AMD EPYC 3251 has a relatively simple topology. There is a single Zen die so the architecture looks largely like the mainstream AMD Ryzen platform actually.
You can see the various cache sizes here, as well as the PCIe root that goes into the die. We took this snapshot with just the OS SSD installed, not with the full test configuration. Still, one can see the basic setup of the core structure. For some perspective, we are essentially seeing this Zen die shot logically presented and flipped 90 degrees.
You can see the CCX and cache structures in that die shot. The topology diagram also matches with the Zen CCX complex overview slide.
One commonly voiced concern on the AMD EPYC 7000 series is the four NUMA nodes. The 8 core, and below, AMD EPYC 3000 series parts like the AMD EPYC 3251 are single NUMA node designs. The larger AMD EPYC 3000 series parts are made from two dies and should have two NUMA nodes. Intel in comparison is still a single NUMA node on all of its current Xeon D designs.
Next, we are going to look at the AMD EPYC 3251 benchmarks. After that, we are going to discuss power consumption as well as market positioning before concluding with our final thoughts.