IBM running Power5 prototypes

IBM confirmed Tuesday that the first silicon prototypes of its mutlithreaded, multicore Power5 microprocessor are up and running in its labs.

"We've already booted AIX, Linux and OS/400," said IBM director of technology assessment Joel Tendler. "We're deep in the middle of test cycle."

When it starts being offered in IBM's pSeries systems next year, the Power5 will have a clock speed "slightly better" than 2GHz, and some "slight increases" in memory cache size over IBM's current Power4 processors, according to Tendler. But the chip's major innovation will be the addition of symmetric multithreading, a feature that allows a single processor to behave like a dual processor as far as applications are concerned. This can improve the performance of some applications by as much as 40 percent, Tendler said.

IBM's symmetric multithreading is similar to the Hyper-Threading technology that Intel has made available with its Pentium 4 processors, according to Nathan Brookwood, principal analyst with the Insight 64 research company in Saratoga, California.

"IBM was the first guy to do multiple cores on a chip, and Intel was the first guy to do symmetric multithreading on a chip," Brookwood said. "The next logical step is to do multicores with multithreading, and it looks like IBM, with the Power5, will be the first guy on the street to do that."

Symmetric multithreading keeps processors busier by letting them use clock cycles that would normally go to waste when a chip's cache is waiting for more information to be transferred from a computer's memory. It typically delivers performance enhancements in the 20 percent to 40 percent range, Brookwood said.

The first Power5 chips will be based on 130 nanometer process technology, meaning that the smallest features on these chips will be 130 billionths of a meter wide. In 2005, IBM will go to a 90 nanometer process, Tendler said.

Improvements to the AIX operating system planned for around the time the Power5 is released will allow users to turn the multithreading feature on or off. Users of high performance or technical applications might want to run the new processors in single threaded mode, Tendler said. "There are cases when you don't run from memory, so the only thing holding up execution is how fast you can drive the processor."

IBM is also developing some dynamic power management features that will help the chips generate less heat, Tendler said.

Looking beyond the Power5, IBM's Power6 processor is expected to appear in 2006, he said.

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