DelayDroid: an instrumented approach to reducing tail-time energy of Android apps

Mobile devices with 3G/4G networking often waste energy in the so-called “tail time” during which the radio is kept on even though no communication is occurring. Prior work has proposed policies to reduce this energy waste by batching network requests. However, this work is challenging to apply in practice due to a lack of mechanisms. In response, we have developed DelayDroid, a framework that allows a developer to add the needed policy to existing, unmodified Android applications (apps) with no human effort as well as no SDK/OS changes. This allows such prior work (as well as our own policies) to be readily deployed and evaluated. The DelayDroid compile-time uses static analysis and bytecode refactoring to identify method calls that send network requests and modify such calls to detour them to the DelayDroid run-time. The run-time then applies a policy to batch them, avoiding the tail time energy waste. DelayDroid also includes a cross-app communication mechanism that supports policies that optimize across multiple apps running together, and we propose a policy that does so. We evaluated the correctness and universality of the DelayDroid mechanisms on 14 popular Android apps chosen from the Google App Store. To evaluate our proposed policy, we studied three DelayDroid-enabled apps (weather forecasting, email client, and news client) running together, finding that the DelayDroid mechanisms combined with our policy can reduce 3G/4G tail time energy waste by 36%.摘要创新点智能手机在 3G/4G 网络条件下的待机时间主要取决于应用后台网络请求。 已有的工作提出了一些节省安卓网络能耗的网络调度算法,然而如何将这些算法自动地实现地现有的安卓应用中是一大挑战。本文给出了一种通过自动程序转换来支持现有的安卓应用中网络请求延迟调度的方法。其核心是应用字节码转换。本文介绍了将安卓应用转换成支持后台网络请求调度的应用的技术挑战、处理机制、以及 DelayDroid 转换系统。与已有的工作相比, DelayDroid 有两大特色:一是程序转换自动执行;二是转换后的应用可支持多应用的后台网络请求调度, 该调度机制可以降低安卓应用的待机耗电。此外, DelayDroid被设计为可对只有 dex 字节码的安卓应用进行转换, 更具实用性。