IBM running Power5 prototypes
by Robert McMillan, IDG News Service

SAN FRANCISCO (08/20/2003) -- IBM confirmed Tuesday that the first
silicon prototypes of its multithreaded, multicore Power5
microprocessor are up and running in its labs.

"We've already booted AIX, Linux and OS/400," said Joel Tendler,
IBM's director of technology assessment. "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 2 GHz, 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%, Tendler said.

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

"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 range
of 20% to 40%, 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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