Intel meshes up Xeon D processors with Skylake Server cores


Two years after Intel introduced the Xeon D family of low-power server platforms, the wave of ARM processors for the data center that those Broadwell system-on-chips were meant to stave off hasn't yet broken. The Xeon D family, then, has most likely succeeded in its mission of providing capable and efficient computing hardware for what's now being called "edge" computing: the last step between large data centers and users on PCs, smartphones, or an increasingly broad range of smart devices. Think a lot of small, lightweight tasks instead of a few big, heavy ones.

The prospect of high-bandwidth, low-latency wireless network access through 5G technologies is going to make edge computing a hot market in the coming years, and a number of companies are still attempting to position many-core ARM CPUs as the answer to that problem. Intel is gearing up to serve the potential wave of edge-computing customers by launching a new generation of Xeon D CPUs powered by its Skylake Server microarchitecture today.


A block diagram of the Skylake Server core

As a quick refresher, the Skylake Server microarchitecture makes a couple big changes to the Skylake core that's been kicking around in various forms since 2015. Skylake Server can execute Intel's ultra-wide AVX-512 SIMD instructions, and its cores are tied together using a scalable mesh interconnect that's meant to make it easier to build many-core CPUs with more predictable memory-access and latency characteristics than the ring bus of older chips. Intel also performed what it calls a rebalancing of the cache hierarchy on Skylake Server cores. Each core now has 1 MB of L2 cache, up from 256 KB per core on client Skylake CPUs. The massive shared L3 cache that typified many Broadwell CPUs falls back to 1.375 MB per core on Skylake Server, however, and that cache becomes a victim for the large L2.

Model Cores Base
frequency
(GHz)
All-core
boost
frequency
(GHz)

Single-core
boost
frequency
(GHz)

TDP Memory
support

Integrated
10 Gb
Ethernet

Integrated
QuickAssist
Technology

Price

Server and cloud SoCs
Xeon D-2191 18 1.6 2.2 3.0 86 W 2400 MT/s No No $2407
Xeon D-2161I 12 2.2 2.8 90 W 2133 MT/s 4x 10 GbE $962
Xeon D-2141I 8 2.2 2.7 65 W $555
Network and enterprise storage SoCs
Xeon D-2183T 16 2.2 2.8 2.8 100 W 2400 MT/s 4x 10 GbE No $1762
Xeon D-2173IT 14 1.7 2.3 3.0 70 W 2133 MT/s $1229
Xeon D-2163IT 12 2.1 2.6 75 W $930
Xeon D-2143IT 8 2.2 2.7 65 W $566
Xeon D-2142IT 8 1.9 2.5 $438
Xeon D-2123IT 4 2.2 2.7 60 W 2400 MT/s $213
QuickAssist Technology SoCs
Xeon D-2187NT 16 2.0 2.4 3.0 110 W 2666 MT/s 4x 10GbE Up to
100 Gbps
$1989
Xeon D-2177NT 14 1.9 2.3 105 W $1443
Xeon D-2166NT 12 2.0 85 W 2133 MT/s Up to
40 Gbps
$1005
Xeon D-2146NT 8 2.3 2.5 80 W $641
Xeon D-2145NT 8 1.9 65 W Up to
20 Gbps
$502

For Skylake Xeon Ds, Intel uses that fundamental building block to construct 14 different products spread across three categories: "edge server and cloud," "network edge and storage," and chips with Intel's QuickAssist accelerator technology on board. Those parts range from four CPU cores to 18 cores with Hyper-Threading and carry TDPs ranging from 60 W to 110 W. Both core counts and TDPs are up considerably from Broadwell Xeon Ds' four to eight cores and "under 20 W" to 45 W thermal ratings. Intel has further boosted these SoCs' 10-gigabit Ethernet interface counts from two to four on the chips that include support for the networking standard, and they'll offer as many as 32 PCIe 3.0 lanes direct from the CPU.

Even though Intel calls these processors systems-on-chips, the Skylake Xeon D family likely incorporates the chipset silicon onto the package rather than onto the processor die. Each of these Xeon Ds will offer partners up to 20 flexible high-speed I/O lanes to play with, each with the equivalent of one PCIe 3.0 lane's worth of bandwidth. Those lanes can be converted directly into 20 PCIe 3.0 lanes, up to 14 SATA 6Gbps ports, or up to four USB 3.0 ports, though not all at once. The Skylake Xeon D platform will also support up to 512 GB of DDR4 RAM with ECC support across four channels with two DIMMs per channel. Maximum RAM speeds will vary by processor, however, as lower-end parts might only support DDR4-2133 and higher-end parts will get full-blown DDR4-2666 support.

AVX-512 support and Intel's QuickAssist Technology (QAT) give Skylake Xeon Ds considerable flexibility for accelerating complementary applications. AVX-512 can boost heavy-duty general-purpose SIMD applications, while QuickAssist tech offloads a range of cryptographic functions for encryption, hashing, and key generation, among others, to dedicated hardware. Intel can dial-a-yield for AVX-512 execution resources, and all Xeon Ds include one AVX-512 FMA unit per core out of a possible two. Chips with QuickAssist support are segmented not only by core count and clock speeds, but also by the amount of bandwidth they can provide to QuickAssist offload. The Xeon D-2145NT offers 20 Gbps of QAT bandwidth at the ground floor, while the 16-core D-2187NT can offer up to 100 Gbps of QAT bandwidth.

As BGA packages, Skylake Xeon D SoCs will require the help of system integrators to be transformed into usable servers. ASRock already has one Skylake Xeon D motherboard on its website, and we expect a wave of announcements from other Intel server partners with these SoCs on board soon. The need for an intermediary to turn these parts into usable systems make these chips' list prices mostly useful as a starting point for understanding Intel's positioning goals, since it'll be impossible to obtain one of these chips outside of a server or server motherboard. We'll be keeping an eye open for servers and server boards built around these new Xeon Ds as time goes on. Thanks to TR tipster SH SOTN for pointing us to the ASRock motherboard linked above.

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