Cool Fusion: AMD's plan to revolutionise multi-core computing

AMD's Fusion roadmap calls for the first processors based on this new architecture to ship late 2008/early 2009, out into the 45nm era. Laying the groundwork will be the series of platforms AMD has in mind to promote, each combining multi-core CPUs and one or more separate GPUs to show how mixing and matching these elements will allow vendors to tailor systems better for certain applications. Come Fusion, and the same logic will apply, only this time the choice is which processing unit you buy for a given system rather than which mix of system components.

Not that the discrete GPU is going to go away. Both Drebin and Hester stress certain apps need raw GPU horsepower, and since these chips remain a strong part of ATI's and now AMD's business, you'd hardly expect either man to play it down more than two years before Fusion's due to debut.

What Fusion represents, then, is the shift of the integrated graphics core off the North Bridge and onto the CPU, improving the speed of its link to the main core and the memory controller, and reducing system power consumption into the bargain.

That said, it might not be unrealistic to expect multi-core Fusion-based GPU-only chips appearing on future add-in cards, or multi-GPU Fusion processors driving gaming-centric PCs. Much depends on how well AMD can build powerful graphics core into the Fusion architecture and whether, come 2008/2009, it reckons there's business advantage to be gained by keeping Fusion GPUs back a generation, as is the case with integrated graphics today.

AMD's ambitions stretch beyond gaming and scientific computing, and Hester talks about Fusion processors extending from the consumer electronics world right up to high-performance computing environments, from palmtops to supercomputers, as he puts it.

Intel's ambitions are not so very different. All its forecasts point to driving the x86 instruction set well beyond the PC and server spaces out into mobile and consumer electronics applications. If Intel financial woes earlier this year hadn't suggested the sale of its XScale ARM-based processor operation, the company's strategic emphasis on x86 would have made the move inevitable.

The battle lines are drawn then not on the basic ISA but on how to extend it with new features to meet emerging computing demands. Given what Intel has said to date, it's focusing on a multi-core future that deliver sufficient processing resources to deliver GPU-like functionality through ISA extensions. Intel's plan for SSE 4, due to debut in the 45nm 'Penryn' timeframe, is a case in point.

Both companies have the transistor budgets to drive each's approach, one bringing more technology off system onto the processor, the other expanding the CPU power of the chip. The issue for Intel will be whether its reliance on the North Bridge will deliver it sufficient bandwidth to make its approach run smoothly enough. Only time will tell - it has already been rumoured to be developing on-CPU memory controllers.

Roll on round two of the multi-core contest. ®