Leave your beer and pizza at the door, please (Image: Air Force Research Lab)

The US Air Force Research Lab recently put out a request for 2200 Sony PlayStation 3 games consoles. The military researchers want to wired them up with the 300 or so they already have to make a type of supercomputer never seen before.

But it won’t be the ultimate gaming system to teach pilots how to blast enemies out of the sky. Instead it will analyse radar and simulate the workings of brains.

The consoles are desirable because of the unique abilities of the chip at their heart. Jointly designed by Sony, Toshiba and IBM, the Cell chip is designed for the speedy and efficient graphics processing that gaming requires, as well as for number crunching.


Big iron

The supercomputer that was until last month the world’s fastest, Roadrunner, was built by IBM using 12,000 Cell chips. But to get world-beating performance, those chips were combined with 6000 extra processors typically used in servers, 113.91 terabytes (more than 100,000 gigabytes) of storage and high-speed data links, which put the total cost at $120 million.

The air force, by contrast, won’t be starting with the high-performance versions of Cell chips used in Roadrunner. Instead it will simply line up its thousands of complete PS3s on racks and connect them via the standard Ethernet ports. “Our interest was to see what we could get on a much more limited budget,” says Richard Linderman, senior scientist for advanced computing architecture at the air force lab in Rome, New York. Since April 2008 the lab has been testing an array of 336 PlayStations that cost $360,000 in total.

“The best feature was a low price – $400 per unit – which has since dropped to $300,” Linderman says. The not-so-good features were hardware limitations, such as the chips having only 256 megabytes of random-access memory built on, and a data-transfer rate just 1/10th that of Roadrunner.

Go slow

Without modification, the PlayStations can also only perform calculations using numbers encoded using 32 bits, rather than the more accurate 64-bit operations of Roadrunner. But although unsuited to the simulations of climate or nuclear weapons that are usual for the largest supercomputers, the new machine will have other uses.

The trial PS3 cluster excelled at image enhancement, processing high-definition video and analysing radar signals, says Linderman. It’s also well-suited for air force studies of large-scale “neuromorphic” processing that simulates the working of the human brain.

The new cluster, bigger than any assembled before, will also be able to run at full power in “interactive mode”, meaning a user can give it new instructions while it is still at work in response to its results so far, just as we interact with a desktop computer. In contrast, supercomputers typically run in “batch mode” and must complete the task they are set without interruption.

Cheap power

Linderman says the completed network should offer one-fifth of Roadrunner’s computing power for 1/60th the price – just $2 million.

Massachusetts Institute of Technology computer scientist Charles Leiserson, not involved with the project, says the approach makes sense. Wherever possible, “build your system around commodity components”, he says.

The cluster should handle jobs such as image processing well because they can be broken down into independent parts, avoiding the data bottleneck of the standard network links between consoles, he says. “It could be a very cost-effective way of solving those problems,” he told New Scientist.