I think we can all agree that smartphones are incredibly useful, and their benefits are only compounded by the wide range of applications we can download. However, a study has revealed that free applications can consume a whopping 75% more energy than paid applications – mainly due to ads.
However, a study entitled “Where is the energy spent inside my app?” by computer scientist Abhinav Pathak of Purdue University, Indiana, states that these free apps are draining our smartphone batteries, as ads are consuming up to 75% more energy by tracking user information and conducting other hidden tasks unrelated to the application’s core functions.
Pathak’s team made the discovery after creating Eprof, the first fine-grained energy profiler for smartphone apps. The program was then tested on an assortment of smartphones running Android and Windows Phone 7 (strangely though, the iPhone escaped judgement, perhaps because its battery life is already famously low).
Using a team of applications, from the popular but paid-for Angry Birds to the free Chess and Facebook apps, the team found that only 10 to 30 percent of the energy was spent powering the app’s core function.
According to the study, “In Angry Birds only 20 percent is used to display and run the game, while 45 per cent is spent finding and uploading the user’s location with GPS, then downloading location-appropriate ads over a 3G connection. The 3G connection stays open for around 10 seconds, even if data transmission is complete, and this ‘tail energy’ consumes another 28 per cent of the app’s energy.”
The study also revealed several “wakelock bugs”, a family of ”energy bugs” in smartphone apps, and effectively pinpointed their location in the source code. Not only does this raise certain privacy issues, but Pathak believes that the energy inefficiency lies at the core of the third-party code that developers use to generate profit on free apps.
“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. As such, optimising the energy consumption of millions of smartphone apps is of critical importance,” he writes in his study. “However, the quarter million apps developed so far were largely developed in an energy oblivious manner.”
There is however a solution. As the problem is code-based, it can be fixed fairly easily and Pathak’s team have already been able to reduce the energy consumption of four apps by 20 to 65 percent using a new accounting presentation of app I/O energy.