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DARPA Targets Computing's Achilles Heel: Power
coondoggie writes "The power required to increase computing performance, especially in embedded or sensor systems has become a serious constraint and is restricting the potential of future systems. Technologists from the Defense Advanced Research Projects Agency are looking for an ambitious answer to the problem and will next month detail a new program it expects will develop power technologies that could bolster system power output from today's 1 GFLOPS/watt to 75 GFLOPS/watt."
No, the problem is getting hold of raw materials for batteries. Mobile computing is on the rise and the west doesn't want to be too dependent on foreign mineral deposits. More efficient computers = smaller batteries = smaller amounts of lithium etc needed.
The problem is not just generating the power... it's delivering it and consuming it without breaking/melting. And that's what they're getting at here - getting more FLOPS per watt... not finding out how to push more watts into a system. A silly amount of the energy going into a supercomputer comes out as heat... and a silly amount of energy is then used to remove that heat. Hopefully, by significantly improving the energy efficiency of chips and systems, we can make them a lot more powerful without them needing a whole lot more power. And I haven't even mentioned the mobile/embedded side of the spectrum where its about battery life and comfortable operating temperatures... the same energy efficiency goals apply.
This is the sort of thing we over the pond are very interested in too. Like for example *cough* the Microelectronics Research Group that I'm a part of.
The amount of computation done per unit energy, isn't really the issue. Instead the problem is the amount of _USEFUL_ computation done per unit energy.
The majority of power in a modern system goes into moving data around, and other tasks which are not the actual desired computation. Examples of this are incrementing the program counter, figuring out instruction dependancies, and moving data between levels of caches. The actual computation of the data is tiny in comparison.
Why do we do this then? Most of the power goes to what is informally called the "Turing Tax" - the extra things required to allow a given processor to be general purpose - ie. to compute anything. A single purpose piece of hardware can only do one thing, but is vastly more efficient, because all the power used figuring out which bits of data need to go where can all be left out. Consider it like the difference between a road network that lets you go anywhere and a road with no junctions in a straight line between your house and your work. One is general purpose (you can go anywhere), the other is only good for one thing, but much quicker and more efficient.
To get nearer our goal, computers are getting components that are less flexible. Less flexibility means less Turing Tax. For example video encoder cores can do massive amounts of computation, yet they can only encode video - nothing else. For comparison, an HD video camera can record 1080p video in real time with only a couple of Watts. A PC (without hardware encoder) would take 15 mins or so to encode each minute of HD video, using far more power along the way.
The future of low power computing is to find clever ways of making special purpose hardware to do the most computationally heavy stuff such that the power hungry general purpose processors have less stuff left to do.
In a pinch you can extract lithium from sea water. That's basically what a lithium deposit is... an old sea that dried up and left the salts. Lithium isn't a big fraction of a battery's cost, weight or volume. Please everyone stop being silly. The cobalt that is often used in lithium batteries is far more expensive, rare and used in larger proportions. We just don't call them cobalt batteries so no one knows about that part.