There's a new chip war on the way. Inside the massive data centers that power the internet, most machines are driven by microprocessors from Intel, and it's been that way for years. But in the coming months, an army of chip makers hope to challenge the Silicon Valley behemoth with a new breed of processor based on the ARM architecture, the same basic chip design that drives so many of the world's smartphones.
These chips promise to significantly reduce the power consumed by the modern server, and that's certainly an attractive prospect for Facebook and other companies that now run their web services atop tens of thousands of machines. But Intel has an answer. The chip giant is preparing its own low-power server processors based on the Atom chips it originally built for mobile devices.
Which chip architecture is better suited to this brave new world of low-power server chips? Well, we're still waiting for the serious chips to arrive. But according to a new paper from researchers at the University of Wisconsin, Madison, neither architecture has an inherent advantage over the other -- at least not where power consumption is concerned.
Although things like transistor count, voltage and clock speed have a big effect on a chip's power efficiency, the University of Wisconsin researchers took a close look at something else. They studied the chips' instruction sets -- the rules that define the basic operation of the processor.
ARM chips and Intel chips use different instruction sets. That's the fundamental difference between the two competing products. But tests run by the researchers indicate that when it comes to fundamental energy efficiency, both instruction sets are in the same ballpark. "There was not much of a difference," says Karu Sankaralingam, the Wisconsin professor who led the project. "One company is not building significantly more efficient designs than another company."
The paper was presented late last month at computer research conference in China.
The research team -- which also includes graduate students Emily Blem and Jaikrishnan Menon -- tested ARM chips based on the Cortex A8 and the Cortex A9 architecture, an Intel Atom chip, and Intel core i7 chip, a beefier processor that -- unlike the others -- was originally designed desktop and notebook machines. The i7 chip consumes more power than the others, but it's built for higher performance. According to Blem, when running server-style workloads, the ARM and the Intel Atom chips exhibited very similar power consumption.
The team did not look at newer ARM designs, including the 64-bit ARMv8 architecture, but they believe the results would look much the same -- in terms of the relationship between power and performance.
Of course, the difference in instruction set will affect things in other ways. A move to ARM will require some changes to software running atop today's servers. Forrest Norrod -- who oversees the server business at Dell, one of the world's largest server sellers -- questions whether companies will want to maintain two software platforms (one for ARM and one for Intel). But this is a separate issue.
If the two camps are on similar footing -- power-wise -- does this mean there's not a war on the way? Hardly. The larger point is that these new ARM server chip provide the Facebooks of the world with more choice -- and that can't be underestimated.
