has built a 512-node prototype of its Blue Gene L supercomputer that has been ranked as the 73rd most powerful computer in the world. The machine, which is capable of a peak performance of 2 trillion floating-point operations per second (teraflops), is about the size of a 30-inch TV.
The Blue Gene L supercomputer, which is being built by IBM for Lawrence Livermore National Labs, will be the first major system to be built under IBM’s Blue Gene research project, which was launched in 1999. The project’s goal is to ultimately build a computer capable of a petaflop, or one thousand trillion operations per second, about 25 times as fast as the most powerful computer today, the 41-teraflop Earth Simulator supercomputer.
The key to Blue Gene’s ability to extract such performance out of such a small amount of real estate is the embedded PowerPC processor that IBM researchers have designed for the machine. Each Blue Gene chip contains dual floating-point processors, 4M bytes of L3 memory, and five network controllers.
“It’s really this system-on-a-chip technology,” said Bill Pulleyblank, the director of exploratory server systems for IBM research.
The system-on-a-chip approach means that Blue Gene’s nodes do not contain the kind of features typically found in commodity systems — disk drives or sound cards or microphone jacks — and require far less space and power than other computers. “You don’t have a lot of extraneous stuff that you’re trying to cool,” said Don Dossa, a computational physicist with Lawrence Livermore who is working on the project. “We have processor, memory, and communications.”
The 700MHz processors have a peak power consumption on the order of 10 to 15 watts per node, said Dossa.
Blue Gene’s heat management is further enhanced by a unique design that will give the supercomputer a tilted look, like a row of dominos simultaneously tilted to one side. “The real secret is by using these low-power processors and by doing some careful engineering on it, we’re able to air-cool the machine,” said Pulleyblank. Because of these two elements, Blue Gene requires about one-tenth the cooling of a typical supercomputer, he explained.
When Blue Gene L finally ships to Lawrence Livermore’s Terascale Simulation Facility building a year from now, the 65,000-node machine will take up 2,500 square feet, less than one-tenth the area of the Earth Simulator, according to Dossa.
Now that Blue Gene’s hardware is working in prototype at IBM’s Thomas J. Watson Research Center in Yorktown Heights, N.Y., the research team is now turning its focus to developing the software tools that will allow applications to run across 65,000 processors at the same time.
“We have a number of challenges facing us in terms of usability,” said Dossa “A lot of the software people know that their algorithms will not scale that way, so they have to rethink their algorithms,” he said.
Lawrence Livermore scientists plan to use the supercomputer to perform extremely accurate calculations on the dynamics of fluids and molecules at the atomic level, as well as dislocation dynamics, or the study of how certain materials can actually be strengthened through defects.
Some of Blue Gene L’s software will eventually be used as part of a larger application designed to simulate nuclear explosions under the U.S. Government’s Stockpile Stewardship program, said Mark Seager, Lawrence Livermore’s principle investigator for ASCI (Accelerated Strategic Computing Initiative) platforms. “Our strategy for Blue Gene, actually, is to focus on some of the key science aspects as separate entities, and then later factor that into the weapons code for the next generation machine,” he said.
Seager’s plans also depend on IBM’s ability to build a working system that is 128 times larger than its current prototype.
Seager believes that the potential cost savings are worth the risk. Blue Gene L, which will deliver between 180 teraflops and 360 teraflops, will cost between US$50 million and $100 million to complete, or about $200,000 per teraflop, Seager said. Lawrence Livermore’s ASCI Purple supercomputer, by comparison, will cost between $1 million and $2 million per teraflop, he said.
While Seager characterizes Blue Gene L as a “high risk” attempt to build an affordable supercomputer, it is one that could help the lab’s work on the Stockpile Stewardship program. “At this point, we’re confident that it will have an impact on the program,” he said.