The Future of Processors, Painted in Multi-Core Colors

Processor designers have agreed upon the fact that multi-core processors will dominate the market in the upcoming years, but failed in achieving consensus on how to implement them. The discussions took place at yesterday's International Solid State Circuits Conference, with participation from senior chip designers from Advanced Micro Devices, IBM, Intel, Renesas, Sun Microsystems and startup Tilera.

According to Chuck Moore, an AMD senior fellow, the future multi-core chips should imitate cellphone processors, that use a large array of specialized cores that are able to run modular software under the control of a programming interface.

"We foresee a move from compatibility based on instruction set architecture to compatibility based on an API," said Moore. "You get an order of magnitude better power efficiency by going to heterogeneous cores. Already Microsoft's DirectX APIs tackle a wide variety of graphics processors, so this is a mature software model," he added.

Renesas' representative, senior chief engineer Atsushi Hasegawa would agree with Moore's idea and supported the cellphone processors comparison. Brad McCredie, a chief microprocessor engineer at IBM said that the future CPUs will undergo some experiments with on-chip accelerators, just like IBM's Cell processor, that powers Sony's PS3. However, he claims that the architectures will end up using a few specialty cores placed in the vicinity of general-purpose ones.

Tilera's founder and chief executive, Anant Agarwal said that multi-core chips cannot be differentiated, and it would be best if they were collections of general-purpose cores. This way, the underlying software model will be maintained at a simple level.

"I would like to call it a corollary of Moore's Law that the number of cores will double every 18 months," said Agarwal whose company currently ships a 64-core embedded processor. He also stated that embedded processors will feature 4,096 cores, while server chips could reach 512 cores by 2017. Desktop chips will be the least powerful, with "just" 128 cores per unit.

The multi-core designs will implement true server farms on a single silicon die and will impressively reduce the necessary space for the future datacenters. According to Agarwal, this kind of computers could run complex software to deal with facial recognition software, for instance.

Sun's estimations were a little more modest and alleged that servers will feature between 32 and 128 cores by 2018. This may seem an artificial opinion, given the fact that Sun is the undisputed world leader when it comes to packing multiple cores into a single die. "I think we can support 500 to 1,000 threads per core. In fact, that may even happen in the next five or six years," claimed Rick Hetherington, chief technologist in Sun's microelectronics group.