How Sony's Development of the Cell Processor Benefited Microsoft

The Wall Street Journal is running an article about a recently released book entitled "The Race for a New Game Machine" which details Sony's development of the Cell processor, written by two of the engineers who worked on it. They also discuss how Sony's efforts to create a next-gen system backfired by directly helping Microsoft, one of their main competitors. Quoting: "Sony, Toshiba and IBM committed themselves to spending $400 million over five years to design the Cell, not counting the millions of dollars it would take to build two production facilities for making the chip itself. IBM provided the bulk of the manpower, with the design team headquartered at its Austin, Texas, offices. ... But a funny thing happened along the way: A new 'partner' entered the picture. In late 2002, Microsoft approached IBM about making the chip for Microsoft's rival game console, the (as yet unnamed) Xbox 360. In 2003, IBM's Adam Bennett showed Microsoft specs for the still-in-development Cell core. Microsoft was interested and contracted with IBM for their own chip, to be built around the core that IBM was still building with Sony. All three of the original partners had agreed that IBM would eventually sell the Cell to other clients. But it does not seem to have occurred to Sony that IBM would sell key parts of the Cell before it was complete and to Sony's primary videogame-console competitor. The result was that Sony's R&D money was spent creating a component for Microsoft to use against it."

Comments

Re:a few facts please?

[TheRaven64]

Even the SPEs aren't exactly built from scratch. They're based on the VMX units from the PowerPC 970 with widened register sets and a modified memory architecture with explicit DMA commands. If the meeting in question took place, I'd imagine IBM showed Microsoft the Cell, the PowerPC 980MP, the 40x, and said 'we can do anything on this spectrum - what requirements do you have?'.

The chip they sold to Microsoft in the end is more or less the same design as the PPU core in the Cell, but that, in turn, is an in-order variant of the 970 with a few bits from the POWER4 that were originally dropped (the 970 itself was a cut-down POWER4 with a VMX unit bolted on) re-added.

IBM would be crazy not to reuse parts of old designs on any new one. They've spent hundreds of millions of dollars creating a library of CPU designs that fit anywhere from a mobile phone to a supercomputer. You're very unlikely to have a set of requirements that they can't meet with a tweaked version of one of their existing designs, and if you really need them to work from scratch then you probably can't afford the final product.

VMX128 in Xenon is borrowed from the Cell SPU's !

[stephen70]

Slashdot users read and learn because anyone who fails to understand the following is uninformed >

The SPU's on the Cell and the PPC Altivec unit on the Xenon(X360) are very closely associated never before has IBM done a 128register 128Bit Altivec unit. The 128bit X 128register Altivec VMX128 unit on the Xenon is the best of any CPU it is also an almost perfect subset or cut down version of the Cell's SPU !.

In non braching calculations and assuming no cache misses VMX128 performance is equal to the SPU's performance this is not a coincidence it's a newly shared design feature in both the instruction sets and silicon fab and clearly shows the CPU designers shared alot.

The older VMX is only 32 registers. Only the Xenon PPC cores and Cell's SPU's have this new VMX128 type arrangement with 128 SIMD registers - especially enhanced for multimedia and gaming.

The Cell architecture just isn't that useful

[Animats]

Sony's payback comes when Playstation3 programmers learn to fully utilize the Cell architecture.

As someone else pointed out, if that was going to happen, it would have happened by now.

The fundamental problem with the Cell is that each SPU only has 256KB of RAM. (Not 256MB, 256KB.) Data can be moved in and out of main memory in the background with explicit DMA-like operations. Given that model, you have to turn your problem into a data-flow problem, where a data set is pumped sequentially through a Cell processor. The audio guys love this. It's useful for compression and decompression. It's a pain for everything else.

It's not good for graphics. There's not enough memory for a full frame, not enough memory for textures, not enough memory for the geometry, and not enough processors to divide the frame up into squares or bands. Sony had to hang a conventional nVidia GPU on the back to fix that. It's useful for particle systems. If you need snow, or waves, or grenade fragments, the Cell is helpful, because that's a pipelineable problem.

There are some other special-purpose situations where a Cell SPU is useful. But not many. If each SPU had, say, 16MB, the things might be more useful. But at 256KB, it's like having a DSP chip. The Cell part belongs in a cell phone tower, processing signal streams, not in a game machine. It's a great cryptanalysis engine, though. Cryptanalysis is all crunch, with little intercommunication, so that fits the Cell architecture.

We're back to a historical truth about multi-CPU architecture - there are only two things that work. Shared-memory multiprocessors ("multi-core" CPUs, or the Xbox 360) work; they're well understood and straightforward to program. Clusters, like Google/Amazon/any web farm, also work; each machine has enough resources to do its own work and can live with limited intercommunication. Everything in between those extremes has historically been a flop: SIMD machines (Illiac IV through Thinking Machines), dataflow machines (tried in the 1980s), and mesh machines (nCube, BBN Butterfly). The only exception to this are graphics processors and supercomputers derived from them. That, not the Cell, is cutting edge architecture.

I've met one of the architects of the Cell processor, and his attitude was "build it and they will come". They didn't.