The GreenDroid project presents a novel concept for smartphone users: a CPU custom-designed around the apps (or perhaps types of apps) you (and only you) use the most.
Taylor and Swanson's GreenDroid design sidesteps this by surrounding a processor's main core-the part of a chip that executes instructions-with 120 smaller ones that each take care of one piece of code frequently needed by the apps used most on a phone. Each core's circuits closely mimic the structure of the code on which they are based, making them up to 10,000 times more efficient than a general-purpose processor core performing the same task.
According to Technology Review, researchers at UCSD have developed a piece of software that can analyze a current Android phone and determine which apps, and which CPU circuits the phone is using the most. Then it can dream up a processor design that best takes advantage of those usage habits, creating a CPU that's both faster and more energy efficient.
The original impetus behind GreenDroid is that there's only so much you can reduce the voltage in smaller, faster CPU designs before heat becomes an issue. But in every current processor, there's a certain amount of "dark silicon" that goes unused. It's good for mass production purposes, but bad for user-specific performance. GreenDroid wants to get rid of that dark silicon. And while they admit that it's possible a future app would come along in a phone that wouldn't take advantage of the custom processor design, they think those occurences would be few and far between in the 1-2 years that people generally own their phones. [GreenDroid via Technology Review]