College of Computing News

Study Finds Phone Storage Prioritizes Developers Over Users

When a user downloads a new app, they probably use just a few features. In fact, according to a new study, people use only about 10 percent of each app.

School of Computer Science (SCS) alumnus Ashish Bijlani discovered this at the start of his Ph.D. when he tried to install an operating system update and was told he didn’t have enough space on his device.

“I don’t play a lot of games, take a lot of pictures, and have very few apps I installed myself, so I was shocked. I wanted to find out what was going on so I started to look into this,” he said.

Bijlani spent his Ph.D. studying phone storage consumption to confirm how much space apps were really taking up and how little users were actually engaging with them. His solution is to make context-specific storage that follows the behavior of the user.

Studying Storage

To determine how each app uses storage, Bijlani had to download the most popular apps and analyze their consumption. Downloading millions of apps to determine their storage size required a large distributed system. When Bijlani started the project in 2014, he downloaded 1.1 million apps; by 2016 the number was up to 2.2 million.

The team analyzed popular apps released in two-year intervals from 2014 to 2019. When an app becomes especially popular, it often turns into a super app with more features than its initial purpose. For example, Uber may have started as a ride-sharing app, but now offers food delivery and scooter rental.

“Developers add a lot of features so users stay engaged with the app because that’s how they monetize it,” Bijlani said. “But only a few users are going to use the majority of these features.”

Bijlani found that most users engage with just 10 percent of the app after conducting a user study with 140 participants from the University of Buffalo’s phone lab testbed, where researchers can deploy Android changes to participants’ phones and carry out studies.

Since these apps are optimized for performance, storage often gets ignored to the detriment of the user. For example, apps include residual files, such as logs on how users interact with ads, that never get cleaned up. There is no incentive for vendors to maximize storage because they can sell bigger phones or more cloud storage.

Proposing a Solution

The phone lab also showed that though most users take advantage of just 10 percent of the app, they’re not all using the same percentage. With gaming apps, for example, some users are content to play just the first few levels, whereas others play the game to completion.

Bijlani believes apps could be context-sensitive to users’ behavior in the same way they already track screen time and Bluetooth devices. With that in mind, he developed a lightweight storage-tracing tool, Cosmos, that collects traces of how users interact with apps to determine the best customized storage model. For example, if a user only opens the weather app in the morning, then future phones could offload it for the rest of the day.

He presented this research at ACM SIGMETRICS in June. Bijlani co-wrote the paper, Where did my 256 GB go? A Measurement Analysis of Storage Consumption on Smart Mobile Devices, with SCS Professor Umakishore Ramachandran, and University of Illinois Urbana-Champaign’s Professor Roy Campbell.