Linked PS3s Become Supercomputer

By William Jackson

Special to GiN

Sony has donated a handful of PlayStation 3s to a professor at the University of Massachusetts Dartmouth who has used the gaming consoles to build his own supercomputer.

Prof. Gaurav Khanna is using a cluster of eight PS3s to do simulations of the gravitational waves emitted from supermassive black holes as they devour stars. It sounds like it could make a great game, but actually it is rocket science. Khanna's research supports a NASA project to study these "ripples in space time," and the home-brewed supercomputer is a big help in his work.

"My cluster is running code as fast as 200 processors on a supercomputer," Khanna said. Retail cost of the system probably would be less than $4,000, about the cost of running one simulation on a traditional supercomputer. But most of the PS3s in Khanna's cluster were donated by Sony.

The PlayStation 3 lends itself to supercomputing for two reasons.

"One cool thing they did was make the PS3 an open platform," Khanna said. "That opened the possibility of using it for things beyond gaming." The second reason the Cell processor developed by Sony, IBM and Toshiba, which Khanna called a "supercomputer-on-a-chip." Each Cell processor has the capacity of about 25 processors used in traditional supercomputers, giving it a "great potential in raw computing power."

Khanna began working on his in-house supercomputer last year.

"I was lucky that my wife was able to get one for me last Christmas," when they were in short supply, he said. "I was so excited about it. As soon as I got it I started taking it apart and putting Linux on it."

His children, who wanted to use the PS3 to play games, were not as enthusiastic, but "now they have their own," Khanna said.

And Khanna has eight of his own. He has six more on order, to be paid for with a grant from his department. "My goal is to have 16" working in parallel in his cluster.

Building the supercomputer was not difficult, he said.

"The first part, to get Linux on it and make the PS3 a regular computer was easy," he said. "Sony tells you how to do it." More difficult was using the new processor. "I had to do a lot of learning" how to rewrite his code to use the Cell processor capacity. "That took several months of work."

Although the Cell processor is being incorporated in new supercomputers, the PS3 cluster probably will not replace traditional supercomputers, Khanna said.

"The fundamental limitation is the small amount of memory on the PS3, just 512M of RAM," he said. "And it's not expandable. My problems are not very heavy on memory usage, just on raw calculations." But for problems that require a lot of memory, the PlayStation 3 is not likely to be the answer.

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