IBM moves Cell processor to 65nm

IBM Corp. has announced PowerXCell, the next-generation version of its Cell processor specifically geared for computer servers.

The new chip uses 65nm process technology to reduce the power consumption of the previous 90nm chip while maintaining the same 3.2GHz frequency. That allows IBM to get two of the chips on to a single board while keeping board-level power consumption under 250W required by IBM's BladeCenter servers.

PowerXCell 8i will drive the Road Runner system, now under test at Los Alamos National Labs to see if it can become the world's first supercomputer to deliver sustained petaflops performance. Besides cracking the petaflops barrier, IBM hopes hundreds of users will decide to plug into their IBM servers a two-socket board housing the new Cell chips to deliver what IBM calls "supercomputing for the masses."

The new design now supports mainstream DDR2 memory rather than the Rambus XDR memories used in the original Cell. It has also expanded total memory capacity of the chip from 2Gbyte to 32Gbyte to support large data sets required in many high-end technical computing applications.

IBM also expanded support for double precision floating point on the eight specialty cores used on Cell. The chip now delivers up to 190TFlops of double precision floating point performance, five times its previous level, said Jim Comfort, VP of workload optimized systems in IBM's Systems and Technology Group.

In addition, IBM expanded the programming tools and management software to let its BladeCenter systems more easily support servers using both Power or X86 processors along with Cell-based cards. With the tools, users can call a library function to invoke vector processing capabilities of the Cell.

"For example, you can use our API to send Monte Carlo functions to the Cell" without disrupting existing x86 or Power code, said Comfort.

The so-called QS22 adapter card will be available at the end of the month for $9,995. IBM is aiming the cards at seven core markets in real-time analytics and digital media.

"We think the total available market is quite large approaching $8-10 billion," said Comfort. The analytical markets include segments in finance, medical and seismic applications. "There is a real value proposition here," he added.

In digital media, the cards are aimed at transcoding or aggregating content, "everyone wants to get as much H.264 content down for high definition media downs their fixed pipes as possible," he said.

In the future, IBM plans to introduce versions of Cell with 16 and 32 vector processing cores, sticking with multiples of eight. The future chips will be able to run the same code geared for today's chips that have eight vector cores and one IBM Power core as an overall controller.

High-end computing market
The chips could pack two of the current die in a multichip module or be fresh designs on a single die. It is not clear whether Sony might use 65nm versions of Cell to pack two processors into a future PlayStation.

Comfort said IBM plans to continue to use videogame consoles as the vehicle for driving the first iterations of new high-end chips in large volumes that later become available to high-end computing systems in lower volume uses.

Over the past 18 months, IBM has rolled out two versions of single-chip Cell cards for its servers. The company has sold relatively small quantities of the cards so far, in part because they were not tuned fully to the needs of business computing, Comfort said.

The Los Alamos National Labs will use an estimated 16,000 of the new Cell chips in their Road Runner system that hopes to break the petaflop performance barrier. The system would be nearly twice as powerful as the current most powerful system in the world as ranked by the Top 500 list. That system is the IBM BlueGene/L installed at the Lawrence Berkeley Lab.

Road Runner "could be the new fastest machine in the world," said Comfort. "Most of the other petaflops efforts are aiming at coming online next year."

IBM has more than 50 customers working with servers that use the Cell chip. It also has more than 20 partners who have developed tools or software for Cell

- Rick Merritt
EE Times