CPU Clock Rate Control Based on Method Invocation in Foreground Application in Android Smartphone

抄録

Reducing power consumption is one of the most important issues in smartphones, especially for the CPU, since it is one of the most power-consuming devices. Improving the user experience by increasing CPU processing performance are also important. There is a trade-off between reducing CPU power consumption and improving the user experience. Decreasing the CPU clock rate reduces power consumption but degrades the user experience. Increasing the clock rate does the opposite. Therefore, it is desirable to increase the clock rate when and only when CPU resource consumption is high, and decrease it when it is low. However, the kernels of many smartphone operating systems, including the Linux kernel in the Android OS, use a follow-up policy of increasing or decreasing the clock rate after observing an increase or decrease in CPU resource consumption, which does not immediately provide appropriate clock rate control. We believe that predicting CPU usage in the near future will be critical for proper control. In this paper, we focus on the Android OS and propose a method to predict CPU usage in the near future by observing the behavior of foreground applications, and controlling the CPU clock rate based on the prediction. The proposed method modifies Android Runtime, which is the application execution environment, observes application method calls in Android Runtime, and predicts CPU usage in the near future based on these observations. We then demonstrate the effectiveness of the proposed method using our microbenchmark application and an actual distributed Android application.