GreenDroid: Newly Developed Smartphone Chip Uses 11 Times Less Energy Per Instruction

Smartphones are looked upon as the most sophisticated and trendy devices there are on the market nowadays, since mostly everyone wants or uses one.

Still, with the coming of Google’s Android and the freedom from Microsoft’s Windows Mobile, no big changes have been made to green up these devices, as their power consumption grows exponentially.

University of California scientists led by Michael Taylor and Steven Swanson from the Department of Computer Science and Engineering (CSE) at the UC San Diego Jacobs School of Engineering are leading a project that aims to use the current processors’ entire capacity, even using that “dark silicon” – areas of the microchip that aren’t used at the same time with others because they would consume a lot of power, and would greatly reduce the battery time. This is called the “utilization wall”.

They called their newly-developed processor “GreenDroid“, from obvious reasons – it uses Android. All of today’s smartphones use pieces of code over and over again, so what the scientists designed was a software that adapts chips to run the “hot code”, as they call it (e.g. MP3 player, phone tasks, etc), in separate dedicated areas, rather than letting them go through the main processor. The other pieces of code, the “cold code” can be run the classic way.

What’s most interesting in their approach is that their software builds up microchips automatically, adapting to the operating systems’ structure, and the special hardware doesn’t have to be hand-made: “A chip that does MP3 decoding – people can build specialized logic for this by hand, but i’s an enormous amount of effort and this doesn’t scale well. Our approach is automated,” said graduate student Nathan Goulding who presented the team’s GreenDroid chip at HotChips.

Now, the green part: by applying the fore-mentioned techniques, the GreenDroid uses 11 times less energy per instruction than a normal “aggressive” mobile application processor. Accounting for code running outside the conservation core still results in an increase in efficiency of 7.5 times compared to an aggressive mobile application processor, according to the computer scientists’ HotChips presentation.

The greening up of smartphones can also have good consequences in other devices alike, because the technology could be used virtually in any mobile device with limited power resources, saving tons of carbon dioxide per year.