A Different Kind of Cell Division at IBM

IBM has confirmed the end of the road for its Cell Broadband Engine (Cell/B.E.) processor, the hybrid multicore processor used in Sony’s PlayStation 3 console — and little else.

David Turek, IBM’s vice president of deep computing, said in an interview with the German site Heise Online that the current PowerXCell-8i processor will be the last of the line.

Originally, IBM planned for a dual PowerPC processor core with 32 Synergistic Processing Element (SPE). The current design has one PowerPC core and eight SPEs.

Turek also told Heise “the future is hybrid,” alluding to IBM possibly using some of the Cell SPE technology in the Power 7 processor IBM is developing.

In a statement e-mailed to InternetNews.com, an IBM spokesperson noted the Cell’s success in the Roadrunner supercomputer, which is a hybrid of AMD Opteron and Cell processors and was for a time the fastest supercomputer in the world. The PlayStation 3, the primary recipient of the Cell B/E processor, has struggled on the market, but its woes have rarely been blamed on the processor.

“Based on our experience gained from Cell, we now believe that the next generation of computing will rely heavily on the integration of multicore and hybrid technologies,” the company said in its statement. “IBM continues to invest in Cell technologies as part of this hybrid and multicore strategy, including in new POWER7-based systems expected next year.”

IBM said it would continue to manufacture the Cell processor for in the PlayStation3 and “we look forward to continue developing next-generation processors for the gaming market.”

Whether that meant Cell-based or something else, it did not specify.

Jon Peddie, president of Jon Peddie Research, isn’t surprised at the end of the processor’s line.

“The Cell, as novel and as exciting as it was when it was introduced, quickly showed some shortcomings that became obvious,” he told InternetNews.com.

It didn’t have inter-processor communication, nor large enough caches per processing engine — and it lacked a direct connect to global memory like DMA, he said. Plus, all of the processing engines all had to go through the PowerPC core, creating a bottleneck.

“So it was lacking things to make it a robust parallel processor. So as much as people liked it, it didn’t have the power to do all the things people wanted,” Peddie said.

What became the final product “should have been the first engineering model and then ripped apart and critiqued by various parties and redone,” he added. “They probably would have but it’s so expensive to develop a chip like that, and with one customer, they couldn’t justify that.”

Despite its efforts, IBM never got takers for its Cell-based blades beyond Sony, Toshiba and Mercury Systems, a maker of dedicated and embedded high-performance systems.

Going hybrid now makes a lot of sense, Peddie said.

“That would be a lot like AMD’s Fusion, where [IBM] will have the Cell processors embedded with Power 7,” he added, referring to the AMD chip design that will see graphics processing merged into a CPU.

“The trick there will be managing the power consumption budget,” he said. “I think a hybrid solution would be a clever thing to do if they can manage the power consumption budget and make the appropriate design.”

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