Mac Supercomputer: Fast, Cheap

Leander Kahney, WIRED News, reports:

The brand new "Big Mac" supercomputer at Virginia Tech could be the second most powerful supercomputer on the planet, according to preliminary numbers.

Early benchmarks of Virginia Tech's brand new supercomputer -- which is strung together from 1,100 dual-processor Power Mac G5s -- may vault the machine into second place in the rankings of the worlds' fastest supercomputers, second only to Japan's monstrously big and expensive Earth Simulator.

The Big Mac's final score on the Linpack Benchmark won't be officially revealed until Nov. 17, when the rankings of the Top 500 supercomputer sites are made known at the International Supercomputer Conference.

But Jack Dongarra, one of the compilers of a Top 500 list, said Tuesday that preliminary numbers submitted to him suggest Big Mac could be ranked as high as second place.

"They're getting about 80 percent of the theoretical peak," Dongarra said. "If it holds, and it's unclear if it will, it has the potential to be the world's second most powerful machine."

The Big Mac's theoretical peak is 17.6 teraflops, which would easily put it in second place behind Japan's Earth Simulator, a monster machine composed of more than 5,000 processors operating at 35.6 trillion calculations per second.

Dongarra warned that no machine ever performs at its theoretical peak. But even if the Big Mac comes in at 80 percent of its theoretical limit, it still will make No. 2 on the current list.

"We're just making up numbers here," Dongarra cautioned. "We don’t have real numbers yet. If they get 80 percent, it will be slightly faster than (ASCI Q, the current No. 2 on the Top 500 list)."

Built by Hewlett-Packard for the Los Alamos National Laboratory, ASCI Q is based on 8,000 Alpha processors and operates at 13.8 teraflops.

Dongarra said Big Mac's early numbers were based on tests run on 128 processors, or about 5 percent of the machine's total 2,200 processors. "It just gets worse as you add more processors," he said.

Jason Lockhart, associate director of Virginia Tech's terascale computing facility, which built the machine, said final benchmarks have been run but declined to share the numbers.

When asked where the machine would place in the Top 500 rankings, he responded: "We expect the machine to place well. The goal is to be in the top 10. How about that"

Lockhart cautioned that even if Big Mac beat most of the machines in the current Top 10, the list, which is compiled twice a year, is a moving target. Lockhart said there are four or five new supercomputers coming online that also may qualify for places in the Top 10.

If the Big Mac supercomputer turns out to be the second most powerful in the world, it is a remarkable achievement.

The machine is the first supercomputer based on Macs; it is one of the few supercomputers built entirely from off-the-shelf components and it cost a bargain-bucket price -- only $5.2 million. By comparison, most of the top 10 supercomputers cost about $40 million and up. The Earth Simulator cost $350 million.

"It is impressive, absolutely impressive what they've done," said Dongarra. "($5.2 million is) a very low number for a computer of this size and power."

Dongarra said the cost is so low he questioned whether the college got a special discount. Lockhart couldn't be reached for an answer.

Dongarra said in terms of the number of processors, Big Mac's closest analog is a cluster of 2,300 2.4 GHz Xeon processors at Lawrence Livermore National Laboratory. Clocked at 7.6 teraflops, the cluster is currently ranked third. "It will be interesting to see where the G5 comes in comparison to this machine," he said.