"Now, when you have 1,000 independent threads of operation on a node, then the whole system ends up with billion-way concurrency," said Beckman. "The real change is programming in the node and the parallelism to hide latency, to hide the communication to the other nodes, so that requires lots of parallelism and concurrency," said Beckman.
The new systems will require adaptive programming models, said Beckman. Until an approach is settled it is going to be a "disruptive few years in terms of programming models."
Vendors will have to change their approaches to building software, said Harrod. "Almost all the vendors have 50 years of legacy built into their system software -- 50 years of effort where nobody ever cared about energy efficiency, reliability, minimizing data movement -- that's not there, so therefore we need to change that," said Harrod.
Harrod believes the problems can be solved, but that the U.S. will have to invest in new technologies. "We have to push the vendors to go where they are not really interested in going," he said. Harrod said the U.S. can't build a "stunt machine," or a one-off system that has limited usefulness. The exascale effort has to result in marketable technologies, he said.
"If I can do a 20MW exascale system in 500 cabinets that means we have a petaflop in a single cabinet -- that's amazing," said Harrod. Such a result would mean that a petascale system could be small enough to fit in the data closet of an academic department or business unit.
"We have to do a fair amount of research before we can actually start going out and designing and developing these computers," said Harrod. "We actually don't know exactly how to design and develop these computers at this point in time."
Funding for an exascale system remains a question. The U.S. has approved funds cover preliminary efforts, about $73 million, but has not yet allocated exascale program funding.
"We don't anticipate the ECI [exascale] funding to start before 2014," said Harrod.
FY 2014 begins Oct. 1, 2013. But current fiscal problems in Congress, the so-called fiscal cliff in particular, makes Harrod pessimistic about funding for next year. "To be honest, I would be somewhat doubtful of that at this point in time," he said.
"The biggest problem is the budget," said Harrod. "Until I have a budget, I really don't know what I'm doing," he said.
Patrick Thibodeau covers SaaS and enterprise applications, outsourcing, government IT policies, data centers and IT workforce issues for Computerworld. Follow Patrick on Twitter at @DCgov, or subscribe to Patrick's RSS feed. His email address is firstname.lastname@example.org.
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