Thursday, July 16, 2015

Gray Silicon and FPGAs

For the past few years, we’ve all been hearing the discussions about “Dark Silicon.” Besides being a really cool and ominous-sounding label, dark silicon is an issue that threatens to end multicore scaling on ICs. The reasoning goes like this: “Dennard Scaling” has ended. Dennard Scaling is the concept that power density remains constant as transistors shrink, which gives “Koomey’s Law” its teeth. Koomey’s Law says that performance-per-watt in computation has been improving by approximately a factor of two every 1.57 years. 
At the most recent process nodes, the amount of leakage current has caused Dennard Scaling to break down, and power density has been increasing rapidly. Increasing power density on top of Moore’s Law means that even though we can put more transistors on a chip, we can’t let them operate all at the same time without thermal runaway. We have to leave some of them dark at all times - hence, “dark silicon.”

The reason why FPGAs don't suffer from the dark silicon as much as CPUs/GPUs is that the switching is more spread out than in ALU based architectures.
99% BAD HARDWARE WEEK: Intel had obviously a lot of gray reasons for a recent purchase of Altera IP.

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