October 25, 2004 1:14 PM PDT

IBM supercomputing goes retro

By Stephen Shankland
Staff Writer, CNET News

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For decades, high-performance computing customers have used machines with "vector" processors, which excel at certain mathematical operations and can quickly retrieve large amounts of data from memory. But the vast majority of business computers--and indeed most supercomputers today--use a "scalar" design better adapted to general-purpose computing.

IBM now plans to bridge that divide using a feature of its new Power5 processors. With a technology called Virtual Vector Architecture, or ViVA, the 16 processor cores of a scalar server such as IBM's Power5-based p5-570 can be yoked together to act like a single vector processor.

"We can take a 16-way and run it as a vector," Power5 designer Ravi Arimilli said.

Such a system would have 32 parallel calculation engines, called floating-point units, and if there's sufficient demand from top-drawer customers such as national laboratories, IBM could build necessary software tools to create larger systems, he said.

IBM is trying to keep quiet about its ViVA effort. Company representatives declined to comment on details. A publicity effort Monday is devoted to a scalar machine called Blue Gene/L, with which IBM has claimed the top spot for now in a supercomputer speed test.

Hewlett-Packard and IBM, which together dominate the high-performance computing market, today sell only scalar machines, but vector machines, including Cray's X1 and NEC's SX-8, are still available. And despite threats from IBM and SGI, NEC's Earth Simulator vector system has led a list of the 500 fastest supercomputers for two years.

IBM's move has caught Cray's attention. "I'm not worried that IBM's ViVA processors will give true vector processors a run for their money, but I do think it's a good idea," said Steve Scott, an X1 chief architect. "Trying to hook multiple scalar processors into a vector processor is never going to be as effective as a real vector processor."

But the effort doesn't stop with ViVA. A sequel called ViVA-2 should be able to handle all Cray chores, said Bill Kramer, general manager of the National Energy Research Scientific Computing Center (NERSC) in Berkeley, Calif., whose researchers urged IBM to add ViVA and are collaborating in its development through a program called Blue Planet.

"ViVA-2 is basically putting a scientific accelerator very close to the central processing unit," Kramer said. NERSC has proposed to install a machine called LCS-2 in 2007 with Power6+ processors and ViVA-2 that can perform 50 trillion calculations per second.

The present trend in high-end computing is to link dozens or even thousands of scalar computers together into a massive cluster. While that approach is good for some tasks, vector machines have kept the lead in some areas, IDC analyst Chris Willard said.

"They have advantages in ease of programming," Willard said. And they excel at mathematical operations involving collections of numbers called matrixes--a "fundamental operation in a lot of technical computing."