⇡ # Introduction
Serious changes have taken place in the server and supercomputer market in recent years, and the main one is the emergence of heterogeneous computing and micro servers.
When you look at the rating of TOP500 supercomputers, it becomes clear that every year not only the number of heterogeneous supercomputers grows, but “classical” supercomputers based on CPUs go down lower and lower, giving positions to heterogeneous clusters. That is, the modern supercomputer market requires not unified powerful processors, but highly specialized ones that allow to raise both the performance and energy efficiency of the computer complex to a new level – for example, not so long ago the system based on Xeon E5 processors and Xeon Phi coprocessors showed a record level of energy efficiency in the TOP500.
Ignore these trends is impossible if you want to stay on the market – AMD company, having bought the ATI graphics card manufacturer in 2006, solved the problem with coprocessors, releasing professional devices for GPGPU-computing. The company Intel, not having under its wing developer graphic accelerators, went its own way – starting from scratch the development of an ambitious project Larrabee, which was subsequently transformed into Intel MIC and high-performance coprocessors Xeon Phi. De-facto Intel was able to respond to the needs of the supercomputer market and, apparently, very successfully – according to the TOP500 2013 rating, the most productive supercomputer is based on Xeon E5 processors and Xeon Phi coprocessors.
The microserver market also needed a specialized device, like the supercomputer market. Since processors with low power consumption and high energy efficiency were needed, the classic powerful and complex x86-core Xeon E3 / E5 / E7 and Itanium were clearly not suitable. AMD Company took the path of least resistance – bought a license for ARM-architecture, which is distinguished by its “simplicity” and high energy efficiency. The decision of Intel was clear right away – if in the market of mobile phones, tablets, supercomputers, it did not abandon the x86-architecture, then what about microserver? Since responding to market requests quickly, there was no question of developing the architecture from scratch – as the starting point was taken “ubiquitous” Atom. Adapted for server needs in 2012 microarchitecture Saltwell, Intel received a series of processors S1200, code-named Centerton. These were dual-core processors, produced on a 32-nm process technology. Due to low performance, the need for additional binding (controllers Ethernet, SATA, USB) and limiting the maximum RAM size by 8 GB, this series has not received much distribution. This decision was a breakthrough in the microserver market, so it was short-lived.
In 2013, making work on the bugs, Intel is releasing a new line of Atom S2000 processors – now the chip includes not only eight processor cores with redesigned architecture and PCI, but also SATA, USB, Ethernet and PCI Express controllers, that is, it is a full-fledged SoC.
Despite the fact that Intel significantly reworked the Atom core, the predecessor left an asymmetric layout of the first level caches: the instruction cache in the volume of 32 KB, the data cache – 24 KB. Which is very strange.
The Atom C2000 processor core itself has a Silvermont architecture, which we recently considered. Therefore, it makes no sense to do this again, but the structure of SoC due to the cardinal changes is worth exploring in detail.
SoC Bay Trail includes up to four processor cores, Intel HD graphics with four EU, USB 3.0 and 2.0 controllers, SATA 2.0, PCI Express 2.0 with four lines and a dual-channel memory controller supporting DDR3-1333. In the micro-server as such, there is no need for a graphics core, so the first thing that was excluded from SoC is the Intel HD graphics. Although here it is worth making an amendment – the graphics core as a whole server is necessary, but it requires other functions, for example, IPMI – for this purpose specialized devices like Aspeed AST2400 are used. Theoretically, it was possible to leave Intel HD, “having screwed” to it all the necessary functions, including IPMI, which would allow not only to reduce the number of additional equipment (and thus simplify motherboard layout), but also to have OpenCL support “on just in case “for the” tomorrow’s “heterogeneous calculations. Of course, this would slightly increase the area of SoC, and consequently, the transistor budget, which is usually limited at the time of designing the processor, but the option is still interesting – the competitor in the face of AMD is moving in this direction. However, these are all theories. Total in the SoC Atom C2000 includes:
- to eight processor cores;
- dual-channel DDR3-1600 controller with ECC support;
- PCI Express 2.0 controller with sixteen lines (four controllers with four lines);
- controller with a quartet of SATA 2.0 ports;
- controller with two SATA 3.0 ports;
- four network controllers;
- USB 2.0 controller with four ports;
- cryptographic coprocessor Intel QuickAssist.
It should be mentioned the very series of processors S2000, because it formally contains two types of SoC – Rangeley and Avoton. In fact, these are the same chips with the same architecture, the difference between them is that the Rangeley processors support Intel QuickAssist technology, and Avoton does not. To distinguish processors within the series, Intel uses a different numeric index at the end of the name: the number 8 means the SoC belongs to Rangeley, and 0 refers to Avoton.
Rangeley and Avoton have different market segments: the first are for cloud storage and switching devices, and the latter for micro servers. It is worth noting that Rangeley due to Intel QuickAssist has a recommended cost of $ 37 more than Avoton (for example, C2758 and C2750). Certainly, Rangeley processors can also be used in micro-servers, having overpaid for a cryptographic coprocessor.
⇡ # The Atom C2000 series
The C2000 series currently includes eight Rangeley processors and five Avoton processors. The number of cores in the line varies from two to eight, and TDP – from 6 to 20 watts.
⇡ # Atom C2758 processor specifications
Rangeley performance testing will be performed using the example of the SuperMicro A1SRM-2758F motherboard. It’s worth noting that the motherboard has a twin sister, on which SoC Avoton is soldered, is SuperMicro A1SAM.
|Atom C2758||Atom C2750|
|The technical process, nm||22|
|Number of cores / streams, pcs.||8/8|
|The clock speed, GHz||2,4|
|The maximum clock speed with Turbo Boost||–||2.6|
|Memory cache L1i / L1d, Kbyte||8×32 / 8×24|
|Cache L2, Mbyte||4x 1|
|A set of instructions||Intel 64, MMX, SSE, SSE2, SSE3, SSSE3, SSE 4.1, SSE4.2, VT-x, AES-NI, EPT|
|Support for Intel QuickAssist||There are||No|
|The maximum amount of RAM, GB||64|
|The type of memory supported||DDR3, DDR3L|
|The maximum effective frequency of the RAM, MHz||1600|
|The number of memory channels||2|
|Support for ECC||There are|
|The number of lines PCI Express||16|
|Revision PCI Express||2.0|
|The number of USB 2.0 ports||4|
|The number of ports SATA 2.0 / 3.0||4/2|
|The integrated network controller|| 4 x 1000 Mbit / s or
4 x 2.5 Gbps
|The recommended price, $||208||171|
It can be seen from the specification table that Avoton (Atom C2750) has support for Turbo Boost and a slightly lower cost, while Rangeley (Atom C2758) supports Intel QuickAssist technology. In the rest we have the same chips.
In terms of supported instruction sets, the Atom C2000 looks quite modern: Intel 64, MMX, SSE, SSE2, SSE3, SSSE3, SSE 4.1, SSE4.2, VT-x, EPT, AES-NI. For complete happiness, only AVX, AVX2 and FMA3 are not enough, but the support of this set of instructions would result in a fundamental change and complexity of the kernel and caches due to the 256-bit bit depth. Perhaps in the next generations Atom will receive support for 256-bit extensions – after all, the future generation of Xeon Phi, based on a similar to Avoton core, supports 512-bit AVX-instructions. Separately, it should be said that, as in Haswell, Rangeley has a hardware digital random number generator DRNG, which provides high speed random number generation – for example for cryptographic tasks (using the RDRAND instruction). There is also support for the Intel VT-x2 virtualization instruction set, which includes: Intel VT FlexMigration, Intel VT FlexPriority, VPID, VT Real Mode, VMFUNC.
⇡ # Specifications of the SuperMicro motherboard A1SRM-2758F
|The processor||The Atom of the Cryptographer|
|Memory|| Four 240-pin slot for DDR3 SDRAM DIMM
Supports DDR3 1333/1600 memory
Dual-channel memory access possible
Maximum capacity 64 GB
ECC error correction support
|Possibilities of expansion|| 2 x SATA 2.0
4 x SATA 3.0
1 x Fast UART 16550 Serial Port
1 x SATA DOM TPM 1.2 Header
|The interface panel|| 1 x D-Sub
1 x UID Switch
|BIOS||128 MB SPI Flash EEPROM with AMI UEFI BIOS DMI2.3 ACPI5.0 USB Keyboard Support SMBIOS 2.7.1 UEFI|
|Other||3 x 4-pin connectors for connecting fans|
|The food||The main 24-pin ATX power connector|
|The monitoring|| Monitoring of processor core voltages, + 1,8V, + 3,3V, + 5V, + 12V, + 5V Standby, VBAT, RAM
Monitoring of tachometers of fans
Monitoring of temperatures of processor cores
|The form factor and the size of||uATX, 24.4×19.05 cm|
Before examining the motherboard, let us familiarize ourselves with the circuit of switching interfaces on it.
And also with the layout of slots and connectors.
⇡ # Packaging and appearance
The motherboard is supplied in a laconic and unpretentious packaging – it’s worth noting that motherboards for Xeon have a similar design. Of course, do not forget that this is a server solution, not a gaming solution, nevertheless the “corporate” style, in our opinion, should be reworked – at least making the front side more informative.
The motherboard’s configuration as a whole is common: six SATA cables, a fastening and reinforcing plate, a brief information sheet and a “check list”. Need drivers and manual? Welcome to the Web. By the way, it’s even better – the user always gets fresh drivers from the manufacturer’s website, and not “50-year-olds” recorded on the disc.
The motherboard has the form factor MicroATX and, correspondingly, the sizes 24,4х19,05 cm. Undoubtedly, this form factor allows to get a tight layout in the rack, but small dimensions result in design flaws – for example, latches of two of the four slots for RAM are difficult to access, because they interfere with the interface panel. The board is powered by a 24-pin ATX connector, but if you do not use PCI Express slots, you can also use a 20-pin connector. Also on the board, you can see the undisturbed PCI Express x4 slot, which is installed optionally .
A notable feature of the SuperMicro A1SRM is the USB 2.0 port, disconnected directly on the board, next to which are SATA ports: two white SATA 3.0 and four SATA 2.0 – three black and yellow.
ASPEED AST2400 is used as the graphics adapter, so it’s worth forgetting about 3D, but in principle, it’s not necessary, especially in case of NAS.
As we recall, in SoC integrated controller Intel I347 with support for four network interfaces with a speed of 1000/2500 Mbit / s, and as the transceiver is the chip on the board chip Marvell Alaska 88E1543.
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