Today Intel CTO Justin Rattner is demonstrating one of our latest research achievements – an experimental IA microprocessor capable of unprecedented low-power operation. This technology, which we call the Near Threshold Voltage Processor (codenamed Claremont), is a concept IA processor core that can tune power use so low that it can be powered off a small solar cell. This could lead to “greener” computing, more always-on devices, longer battery lives, and energy-efficient powerful many-core processors for use in everything from handhelds to servers and even supercomputers.
The purpose of this chip is to advance near-threshold voltage (NTV) computing and to demonstrate the energy benefits of NTV designs, which promise better energy efficiency. Most digital designs operate at nominal voltages – about 1V today. NTV circuits operate around 400-500 millivolts – very close to the “threshold” voltage at which transistors turn on and begin to conduct current. It is challenging to run electronics reliably at such reduced voltages. To put it simply, the difference between a “1” and a “0” in terms of electrical signal levels become very small, so a variety of noise sources can cause logic levels to be misread, leading to functional failures. The benefit, however, is that energy consumption reaches an absolute minimum in the NTV regime with a sizeable ~5-10X improvement over nominal operation. The key challenge is to lock-in this excellent energy efficiency benefit at NTV while mitigating performance loss.
Several years of research went into realizing our first NTV IA Processor. Extreme sensitivity to power supply and transistor threshold voltage variations complicates NTV design. We had to develop NTV-aware techniques to improve design robustness for reliable operation. We re-designed the on-die caches and logic and incorporated new circuit design techniques and methods to tolerate variations at NTV, while increasing the chip’s dynamic operational range. For this test case, we picked one of our crown jewels – our first super-scalar Pentium core, though the same techniques could be applied to any Intel digital designs in the future.
The result is a “heat-sink free” processor core that can be placed in NTV mode at <10mW with minimum-energy and 5X better energy efficiency. The processor also provides wide dynamic operational range and can run at higher frequencies (~10X) when performance is needed. The new “always-on” – yet “ultra low power state” can keep applications running and is ideal whenever compute demands are modest. While this prototype may not become a product itself, conclusions from the NTV research could lead to the integration of scalable NTV technology across a wide range of future products from mobile to HPC.
NTV technology isn’t just unique to processors. The concepts are promising to a wide range of digital platforms and opens up many new “use conditions”, taking “always on” to a new level. For instance, this could be compelling for smart phones, tablets and other devices allowing “one” design to efficiently scale all the way, obviating the need for heterogeneous architectures. Also, these ultra-low power levels could allow Intel architecture to expand into broader applications like embedded devices, which would include “everyday” devices such as home appliances and automobiles.
In fact, one goal of NTV research is to enable “zero power” architectures where power consumption is so low that we could power entire digital devices off solar energy, or off of the energy that surrounds us every day in the form of vibrations and ambient wireless signals. This gives us unfettered freedom so we can just leave our power cord and chargers behind. NTV research is particularly applicable to self-powered autonomous sensor networks and monitors strewn about our environment allowing computers to “see” and intelligently “react” to the world around us.
Finally, Justin’s keynote highlighted that NTV research is quickly maturing and the processor is a key enabler for Extreme Scale Computing. Extreme scale means getting the most energy-efficient performance for the power spent – achieving 1000x performance at only 10x the power, or perhaps 10x performance at 1/10 the power. This could help us realize massive Exa-scale supercomputers or put trillions of computations per second in our pockets, while being environmentally-aware.