The Current Intel offerings

Before we can discuss the ARM server SoCs, we want to look at what they are up against: the current low end Xeons. We have described the midrange Xeon E5s in great detail in earlier articles.

The Xeon E3-12xx v3 is nothing more than a Core i5/i7 "Haswell" dressed up as a server CPU: a quad-core die, 8MB L3 cache, and two DDR3 memory channels. You pay a small premium – a few tens of dollars – for enabling ECC and VT-d support. Motherboards for the Xeon E3 are also only a few tens of dollar more expensive than a typical desktop board, and prices are between the LGA-1150 and LGA-2011 enthusiast boards. The advantages are remote management courtesy of a BMC, mostly an Aspeed AST chip.

For the enthusiasts that are considering a Xeon E3, the server chip has also disadvantages over it's desktop siblings. First of all, the boards consume quite a bit more power while in sleep state: 4-6W instead of the typical <1W of the desktop boards. The reason is that server boards come with a BMC and that these boards are supposed to be running 24/7 and not sleeping. So less time is invested in reducing the power usage in sleep mode: for example the voltage regulators are chosen to live long. Also, these boards are much more picky when it comes to DIMMs and expansions cards meaning that users have to check the hardware compatibility lists for the motherboard itself.

Back to the server world, the main advantage of the Xeon E3 is the single-threaded performance. The Xeon E3-1280 v3 runs the Haswell cores at 3.6GHz base clock and can boost to 4GHz. There are also affordable LP (Low Power) 25W TDP versions available, e.g. the Xeon E3-1230L v3 (1.8GHz up to 2.8GHz ) and E3-1240L v3 (2GHz up to 3GHz). These chips seemed to be in very limited supply when they were announced and were very hard to find last year. Luckily, they have been available in greater quantities since Q2 2014. It also worth noting that the Xeon E3 needs a C220 chipset (C222/224/226) for SATA, USB, and Ethernet, which adds 0.7W (idle) to 4.1W (TDP).

The weak points are the limited memory channels (bandwidth), the fact that Xeon E3 server is limited to eight threads, and the very limited (for a server) 32GB RAM capacity (4 Slots x 8 DIMMs). Intelligent Memory or I'M is one of the vendors that is trying to change this. Unfortunately their 16GB DIMMs will only work with the Atom C2000, leading to the weird situation that the Atom C2000 supports more memory than the more powerful Xeon E3. We'll show you our test results of what this means soon.

The Atom C2000 is Intel's server SoC with a power envelope ranging from 6W (dual-core at 1.7GHz) to 20W (octal-core at 2.4GHz). USB 2.0, Ethernet, SATA3, SATA2 and the rest (IO APIC, UART, LPC) are all integrated on the die, together with four pairs of Silvermont Cores sharing 1MB L2 cache. The Silvermont architecture should process about 50% more instructions per clock cycle than previous Atoms due an improved branch prediction, the loop stream detector (like the LSD in Sandy Bridge) and out-of-order execution. However the Atom micro architecture is still a lot simpler than Haswell.

Silvermont has much smaller buffers (for example, the load buffer only has 10 entries, where Haswell has 72!), no memory disambiguation, it executes x86 instructions (and not RISC-like micro-ops), and it can process at the most two integer and two floating point instructions, with a maximum of two instructions per cycle sustained. The Haswell architecture can process and sustain up to five instructions with "ideal" software. AES-NI and SSE 4.2 instructions are available with the C2000, but AVX instructions are not.

The advantages of the Atom C2000 are the low power and high integration -- no additional chip is required. The disadvantages are the relatively low single-threaded performance and the fact that the power management is not as advanced as the Haswell architecture. Intel also wants a lot of money for this SoC: up to $171 for the Atom C2750. The combination of an Atom C2000 and the FCBGA11 motherboard can quickly surpass $300 which is pretty high compared to the Xeon E3.

ARM, Micro and Scale-out Servers The ARM Based Challengers: AppliedMicro
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  • beginner99 - Tuesday, December 16, 2014 - link

    Agree. I just don't see it. What wasn't mentioned or I might have missed is Intels turbo technology. Does ARM have anything similar? Single-threaded performance matters. If a websites takes double the time to be built by the server the user can notice this. And given complexity of modern web sites this is IMHO a real issue. Latency or "service time" is greatly affected by single-threaded performance. That's why visualization is great. Put tons of low-usage stuff on the same physical server and yet each request profits from the single-threaded performance.

    Now these ARM guys are targeting this high single-threaded performance but why would any company change? Whole software stack would have to change as well at don't forget the software usually cost way, way more than the hardware it runs on. So if you save 10% on the SOC you maybe save less than 1% on the total BOM including software. They can't win on price and on performance/watt Intel still hast best process. So no i don' see it except for niche markets like these Mips SOCs from cavium.
  • Ratman6161 - Wednesday, December 17, 2014 - link

    "Xeon performance at ridiculous prices" I just don't get the "ridiculous prices" comment. To me, it seems like hardware these days is so cheap they are practically giving it away. I remember in the days of NT 4.0 Servers we paid $40K each for dual socket Dell systems with 16 GB Ram.

    A few years later we were doing Windows 2000 Server on Dell 2850's that were less than half the price.

    Then in 2007 we went the VMWare route on Dell 2950's where the price actually went up to $23K but we were getting dual sockets/8 cores and 32GB of RAM so they made the $40K servers we bought years before look like toys.

    Four years later we got R-710's that were dual socket/12 cores and 64GB or RAM and made the $23K 2950's look like clunkers but the price was once again almost half at about $12K.

    Today we are looking at replacing the R-710's with the latest generation which will be even more cores and more RAM for about the same price.

    So to me, the prices don't seem ridiculous at all. The servers themselves now make up only a fraction of our hardware costs with the expensive items being SAN storage. But that too is a lot cheaper. We are looking at going from our two SANS with 4GB fiber channel connections to a single SAN with 10GB Ethernet and more storage than the two old units combined...but still costing less than the old SANs did for just one. So prices there are expensive but less than half of what we paid in 2007 for more storage.

    The real costs in the environment are in Software licensing and not I'm not talking about Microsoft or even VMware. Licensing those products are chump change compared to the Enterprise Software crooks...that's where the real costs are. The infrastructure of servers, storage and "plumbing" sorts of software like Windows Server and VMWare are cheap in comparison.
  • mrdude - Tuesday, December 16, 2014 - link

    Great article, Johan

    I think the last page really describes why so many people, myself included, feel that ARM servers/vendors have a very good chance of entrenching themselves in the market. Server workloads are more complex and varied today than they ever have been in the past and it isn't high volume either: the Facebook example is a good one. These companies buy hardware by the truckload and can benefit immensely from customization that Intel may not have on offer.

    To add to that, what wasn't mentioned is that ARM, due to its 'license everything' business model, provides these same companies the opportunity to buy ready-made bits of uArch and, with a significantly smaller investment, build them own as-close-to-ideal SoC/CPU/co-processor that they need.

    Competition is a great thing for everyone.
  • JohanAnandtech - Tuesday, December 16, 2014 - link

    True. Although it seems that only AMD really went for the "license almost everything" model of ARM.
  • mrdude - Tuesday, December 16, 2014 - link

    Yep. And that's likely due to the budget/timing constraints. I think they were gunning for the 'first to market' branding but they couldn't meet their own timelines. Something of a trend with that company. I'm curious as to why we haven't heard a peep from AMD or partners regarding performance or perf-per-watt. Iirc, we were supposed to see Seattle boards in Q3 of 2014.

    I also feel like ARM isn't going to stop at the interconnect. There's still quite a bit of opportunity for them to expand in this market.
  • cjs150 - Tuesday, December 16, 2014 - link

    Ultimately, my interest in servers is limited but I would like a simple home server that would tie all my computers, NAS, tablets and the other bits and bobs that a geek household has.
  • witeken - Tuesday, December 16, 2014 - link

    Who's interested in Intel's data center strategy, can watch Diane Bryant's recent presentation (including PDF): The Q&A from 2013 also has some comments about ARM servers:
  • Kevin G - Tuesday, December 16, 2014 - link

    "Now combine this with the fact that Windows on Alpha was available." - Except that Windows NT was available for Alpha. There was a beta for Windows 2000 in both 32 bit and 64 bit flavors for the curious.

    I disagree with the reason why Intel beat the RISC players. Two of the big players were defeated by corporate politics: Alpha and PA-RISC were under the control of HP who was planning to migrate to Itanium. That leaves POWER, SPARC, MIPs and Intel's own Itanium architecture at the turn of the millennium. Of those, POWER and SPARC are still around as they continue to execute. So the only two victims that can be claimed by better execution is MIPs and Intel's own Itanium.

    While IBM and Oracle are still executing on hardware, the Unix market as a whole has decreased in size as a whole. The software side isn't as strong as it'd use to be. Linux has risen and proven itself to be a strong competitor to the traditional Unix distribution. Open source software has emerged to fill many of the roles Unix platforms were used to. Further more, many of these applications like Hadoop and Casandra are designed to be clustered and tolerate node failures. No need to spend extra money on big iron hardware if the software doesn't need that level of RAS for uptime. The general lower cost of Linux and open source software (though they're not free due to the need for support) combined with furhter tightening of budgets during the great recession has made many businesses reconsider their Unix platforms.
  • JohanAnandtech - Tuesday, December 16, 2014 - link

    My main argument was that the RISC market was fragmented, and not comparable to what the x86 market is now (Intel dominating with a very large software base).

    While I agree with many of your points, you can not say that SPARC is not a victim. In 90ies, Sun had a very broad product range from entry-level workstation to high-end server. The same is true for the Power CPUs.

  • Kevin G - Wednesday, December 17, 2014 - link

    The RISC market was fragmented on both hardware and software. The greatest example of this would be HP that had HPUX, Tru64, OpenVMS, and Nonstop as operating system and tried to get them all migrated to a common hardware platform: Itanium. How each platform handled backwards compatibility with their RISC roots was different (and Tru64 was killed in favor of HPUX).

    The midrange RISC workstation suffered the same fate as the dual socket x86 workstation market: good enough hardware and software existed for less. The race to 1Ghz between Intel and AMD cut out the performance advantage RISC platforms carried. Not to say that the RISC a chips didn't improve performance but vendors never took steps to improve their price. Window 2000 and the rise of Linux early in the 2000's gave x86 a software price advantage too while having good enough reliability.

    Sun's hardware business did suffer some horrible delays which helped lead the company into Oracle's acquisition. Notably was the Rock chip which featured out-of-order execution but also out-of-order instruction retirement. Sun was never able to validate any prototype silicon and ship it to customers.

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