The race to higher server processor performance continues, but the spotlight has largely shifted to the race to lower power consumption. ARM, the undisputed king of low-power processors for mobile applications, has for some time had its sights set on the server market, and its recently revealed ARMv8 architecture gives the company 64-bit clout. But will ARM’s power credentials be enough to take a bite out of the Intel x86 architecture’s dominant share?
ARM’s 64-Bit Architecture Gives Company More Server Credibility
In October of last year, ARM announced its ARMv8 architecture, the company’s first to support 64-bit processing. Although actual devices implementing ARMv8 aren’t expected to appear until 2014, the company is working to build an ecosystem to support the new instruction set, gaining significant support from Microsoft, among others. By moving from a 32- to 64-bit instruction set, ARM opens the possibility of making a real dent in the server market, depending in large part on what server vendors do with the architecture.
The processor IP company is nearly ubiquitous in the mobile-device market, with ARM-based processors appearing in most smartphones and tablet computers, according to PCWorld (“ARM to bite into Intel’s PC dominance by 2015, IDC says”). To meet the need for reasonable—if not long—battery life in mobile devices, the ARM processors have been designed with power efficiency as a high priority, to the detriment of performance to some extent.
Although using an ARM processor in a server wouldn’t have entered the minds of most designers several years ago, the changing focus from performance to energy efficiency has raised the question of whether a lower-power device could be the answer. As data center energy consumption skyrockets and as the operating cost of a server over its lifetime exceeds the capital cost, companies are looking for alternatives to power-hungry servers. ARM hopes this sentiment will give it traction in the server market, which has long been dominated by Intel’s x86 architecture.
Performance Versus Power
Companies are looking for lower power consumption, so by just replacing traditional x86 and similar server processors with low-power ARM processors, the problem is solved, right? Not quite. Power consumption would fall, yes, but so would performance. Simply looking at power consumed is not sufficient, just as with simply looking at performance. Rather than looking at performance (say, in megahertz) or power (watts), a more pragmatic metric would be performance per unit of power consumption (megahertz per watt, for example). At the extremes are traditional x86 server processors, with their high performance and high power, and ARM processors for mobile, with their relatively low performance and low power.
Of course, it’s not a simple matter to increase performance without increasing power: processing tasks require energy, and they will always consume some amount of power. The trick is to balance performance and power to achieve maximum performance per watt—a task that ARM hopes to accomplish by applying its expertise in low-power design. With its new ARMv8 architecture, the company adds a previously missing component to its arsenal: 64-bit processing.
Intel Leads in More than Just Performance
Intel’s x86 architecture has the performance edge, with its server processor design efforts having focused mainly on high performance. The company’s processors have a pretty solid reputation in the industry for being power hogs, but no one disputes their ability to tackle heavy workloads. ARM’s focus on power efficiency, while being an ideal strategy for the mobile market, raises some question as to whether it can achieve sufficiently high performance for server processors while still maintaining its characteristic low power. Likely, the company will make some concessions on both ends in hopes of achieving a maximum performance per watt. But this is not ARM’s only challenge.
In addition to being a performance leader, Intel also boasts a one- to two-generation process technology lead, and its new FinFET transistors are an industry first, giving it an even greater edge in silicon fabrication. This technology lead gives Intel the ability to pack more transistors into a smaller area compared with technologies at competing fabs—including those that manufacture ARM-based processors—yielding lower-power operation and smaller die size for the same performance. Although in the long term, this lead will diminish as the limits of Moore’s Law are reached, assuming the competing fabs stay close to their current paces of development.
Can ARM Really Compete in the Server Market?
Given Intel’s dominant performance and process technology lead, ARM is facing an uphill battle in attacking the server market. ARM processors may also fall short when dealing with heavy workloads, where power-hungry x86 chips may be the best option despite their energy appetites. The main question is whether server vendors can integrate ARMv8-based processors in designs that offer both sufficient performance per watt and the ability to manage large enough workloads to appeal to companies operating data centers.
The recent economic downturn—one from which western nations (in particular, the U.S.) have yet to recover to any significant extent—has brought costs into closer focus. And with inflation pushing energy prices higher, the focus in many industries, including IT and data centers, is on power consumption. This is an advantage for ARM, which gains a significant marketing edge simply from the news. After all, energy costs and higher, ARM uses less energy, so ARM processors are a natural choice for servers. But the marketing must be followed by execution, and we will have to wait until 2014 or later to see whether excitement over ARM processors in servers is justified. Even then, however, ARM will still need time to establish credibility with potential customers and to expand its supporting ecosystem.
Conclusions
ARM offers the potential for a server processor that provides a less power-hungry alternative to the now-dominant x86 architecture. The company’s new 64-bit ARMv8 instruction set makes its architecture more appealing in the server realm, where 32 bits would have been an undesirable limitation. Hoping to exploit its expertise in low-power design and the trend toward greater energy efficiency in data centers, ARM is looking to snag a piece of the server market pie from Intel. Despite the company’s dominance in the mobile market, however, the server market may be a tough row to hoe. The question is now whether ARM can deliver low-power processors; it’s whether ARM can deliver low-power processors with performance sufficient for servers. It may do best catering to certain niche applications rather than broader applications, at least pending more evidence that ARMv8 can compete with x86 in the server space.
Intel is not ignoring ARM’s challenge. To maintain its server dominance, it is also aiming to improve performance per watt by increasing the efficiency of its designs. Ultimately, however, a limit will be reached: processors need power to operate, and the larger the workload, the more power will be required. That’s a simple fact of physics. At best, processor companies can slow the rate of increase of power consumption—but they’re still going to try to pack as much performance as possible into that envelope. Time will tell if ARM is really in the race, or if it will falter at the start.
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About Jeff Clark
Jeff Clark is editor for the Data Center Journal. He holds a bachelor’s degree in physics from the University of Richmond as well as master’s and doctorate degrees in electrical engineering from Virginia Tech.
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