[PAST EVENT] David T. Nguyen: Computer Science Dissertation Defense

November 25, 2014
11am - 1pm
McGlothlin-Street Hall, Room 002
251 Jamestown Rd
Williamsburg, VA 23185Map this location
Despite the rapid hardware upgrades, a common complaint among smartphone owners is the poor battery life. To many users, being required to charge the smartphone after a single day of moderate usage is unacceptable. Moreover, current smartphones suffer various unpredictable delays during operation, e.g., when launching an app, leading to poor user experience. In this dissertation proposal, we provide solutions that enhance systems on portable devices using information obtained from their users and upper layers on the I/O path.

First, we provide an experimental study on how storage I/O path upper layers affect power levels in smartphones, and introduce energy-efficient approaches to reduce energy consumption facilitating various usage patterns. At each layer, we investigate the amount of energy that can be saved, and use that to design and implement a prototype with optimal energy savings named SmartStorage. The system tracks the run-time I/O pattern of a smartphone that is then matched with the closest pattern from the benchmark table. After having obtained the optimal parameters, it dynamically configures storage parameters to reduce energy consumption. We evaluate our prototype by using the 20 most popular Android applications, and our energy-efficient approaches achieve from 23% to 52% of energy savings compared to using the current techniques.

Next, we conduct the first large-scale user study on the I/O delay of Android using the data collected from our Android app running on 1913 devices within nine months. Among other factors, we observe that reads experience up to 626% slowdown when blocked by concurrent writes for certain workloads. We use this obtained knowledge to design a system called SmartIO that reduces application delays by prioritizing reads over writes, and grouping them based on assigned priorities. SmartIO is implemented on the Android platform and evaluated extensively on several groups of popular applications. The results show that our system reduces launch delays by up to 37.8%, and run-time delays by up to 29.6%.

Finally, we study the impact of RAM on smartphone user-perceived performance. This will eventually lead to a mobile memory platform personalized based on users and their usage patterns. Specifically, we investigate how memory affects the performance and how we can maintain optimal memory parameters. Further, the heap usage of several groups of applications is analyzed. In future work, we plan to design and implement a personalized memory system that optimizes the smartphone performance by facilitating the dynamics of usage patterns and RAM parameters.

David Nguyen has been working on his Ph.D. in Computer Science at the College of William and Mary since Fall 2011. He is working with Dr. Gang Zhou, and his research interests include mobile computing, ubiquitous computing, and wireless networking. Before joining W&M, he was a lecturer in Boston for 2 years. He was also a lecturer at Christopher Newport University in 2013. In summer 2014 David was a Mobile Hardware Engineer in Facebook's Connectivity Lab. David received his M.S. from Suffolk University (Boston, 2010), and his B.S. from Charles University (Prague, 2007).