MemSaver: Enabling an All-in-memory Switch Experience for Many Apps in a Smartphone

The availability of diverse applications (apps) and the need to use many apps simultaneously have propelled users to constantly switch between apps in smartphones. For an instantaneous switch, these apps are often expected to stay in the memory. However, when a user opens more apps and memory pressure increases, Android kills background apps to relieve the memory pressure. When the user switches a killed app back to the foreground, the user experiences a laggy response that compromises his experience. To delay this killing under memory pressure for a smoother user experience, we proposeMemSaver, a low-cost approach for preemptively swapping selected pages of the background apps out of memory to avoid or postpone the killing of apps while ensuring their near-ideal switch time. MemSaver uses pages accessed during events similar to the switch and about the same app context for predicting the pages to be accessed in the next switch. Evaluations on OnePlus 9 Pro using representative apps show that up to 60% of app's memory (RSS) can be saved while maintaining the switch time within the acceptable range.