"Eprof tells you how much energy is spent where," Hu explained.

A smartphone app can contain tens of thousands of lines of code, broken down into subroutines, threads, and processes. Eprof maps how much energy comes from each component. It offers researchers and developers a new way to study smartphone energy consumption without using expensive equipment such as a power meter.

"This is the first tool of its kind ever developed for modern smartphones," Pathak said. "We've seen around one million apps written since smartphones emerged roughly five years ago, but there has been no systematic way for the developer to see how much energy the different components consume. Using this tool, you can see what should be changed to improve energy efficiency."

Not only is that good news for developers in the app market--which is expected to reach $38 billion by 2015--but for consumers, too, who should see more efficient apps in the market.

"Despite the incredible market penetration of smartphones and exponential growth of the app market, their utility has been and will remain severely limited by the battery life," the researchers wrote.