PRINCETON UNIVERSITY BOFFINS have developed a 25-core open source processor that can be scaled to create a monster 200,000-core PC stuffed with 8,000 64-bit chips.
The chip is called Piton after the metal spikes driven by rock climbers into mountain sides, and was presented at the Hot Chips symposium on high-performance computing in Cupertino this week.
"With Piton, we really sat down and rethought computer architecture to build a chip specifically for data centres and the cloud," said David Wentzlaff, a Princeton assistant professor of electrical engineering and associated faculty in the Department of Computer Science.
"The chip we've made is among the largest ever built in academia and it shows how servers could run far more efficiently and cheaply."
The current version of the Piton chip measures 6mmx6mm. It has more than 460 million transistors, each as small as 32nm, the bulk of which are contained in 25 cores.
Companies and academic institutions have produced chips with many dozens of cores in recent years, but the readily scalable architecture of Piton can enable thousands of cores on a single chip with half a billion cores in the data centre, said Wentzlaff, adding that more cores ought to mean more processing power.
"What we have with Piton is really a prototype for future commercial server systems that could take advantage of a tremendous number of cores to speed up processing," he said.
At the same time, he suggested, the design could also cut power consumption and therefore heat dissipation.
The programs being run in a typical data centre used by hundreds of thousands or even millions of users rely on similar operations at the microprocessor level. The Piton chip's cores can recognise these instances and execute identical instructions consecutively so that they flow one after another.
This can increase energy efficiency by about 20 per cent compared with a standard core, according to the researchers.
A second innovation is called a memory-traffic shaper that mediates between the demands of different applications accessing memory on the chip. The researchers claimed that this can yield an 18 per cent improvement in performance compared with conventional means of memory allocation.
Piton also assigns areas of the on-chip cache memory to specific cores, while the cores themselves can be reserved or assigned to particular applications.
Generously, rather than creating a startup to exploit the various innovations, Wentzlaff confirmed that the designs will be published under an open source licence.
"We're very pleased with all that we've achieved with Piton in an academic setting, where there are far fewer resources than at large commercial chipmakers. We're also happy to give out our design to the world as open source, which has long been commonplace for software, but is almost never done for hardware," he said.
The architecture has been designed to be easily scalable, enabling it to handle the large-scale repetitive processing tasks increasingly demanded of servers running in cloud data centres. µ
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