Dynamic merging/splitting for better responsiveness in mobile devices

Mobile devices are playing important roles in people's daily life. For mobile devices, system responsiveness is of great importance to keep an impressive user experience. Although new technologies have been developed to improve system responsiveness, mobile devices still suffer from various unpredictable delay. Recently, our evaluation reveals that improper merging operations happen in I/O scheduler layer is an important reason leads to intolerable system latency. In order to mitigate system latency caused by overlarge merged requests, a novel scheme called dynamic merging/splitting based I/O scheduling scheme is proposed. Adding a new unit called "SU" in I/O scheduler, overlarge merged requests are split and re-merged to improve responsiveness of these requests. Evaluation results show that the proposed scheme can effectively improve system responsiveness of android devices. By boosting 20.38% synchronous requests, the latency of small requests are reduced by 35.98%, and large requests are reduced by 48.47% on average. What's more, the worst case latency of synchronous requests are reduced over 90% after optimization.