AppFlow: Memory Scheduling for Cold Launch of Large Apps on Mobile and Vehicle Systems

TL;DR

AppFlow is a comprehensive memory scheduling system for mobile and vehicle devices that significantly reduces cold launch latency of large apps by predicting file access patterns and intelligently managing memory and processes.

Contribution

We propose AppFlow, a novel prediction-based scheduler integrating preloading, reclaiming, and killing strategies to optimize cold launch performance without app modifications.

Findings

Reduces GB-scale cold-launch latency by 66.5%.

Achieves 95% of launches within 1 second over 100 days.

Improves multitasking responsiveness significantly.

Abstract

GB-scale large apps like on-device LLMs and rich media editors are becoming the next-generation trend, but their heavy memory and I/O demands, especially during multitasking, cause devices to reclaim or kill processes, turning warm apps into cold launches. The challenge lies not in storing them, but in fast, accurate launching. For users, 1s is the usability cliff, yet our measurements show 86.6\% of GB-scale cold launches exceed it. Also, Android Vitals flags only $\geq$ 5s as slow, exposing a large satisfaction gap. Existing optimizations are designed in isolation and conflict. For example, preloading reduces I/O stalls but consumes scarce memory and is undone by reclamation, while reclamation and killing free memory but sacrifice background survivability, leading to repeated cold relaunches. Our key insight is that, although multitasking makes runtime behavior complex, each app's file access pattern remains predictable. The challenge lies in exploiting this predictability, i.e., preloading without exhausting memory, reclaiming without undoing gains, and killing selectively to preserve background survivability. We introduce AppFlow, a prediction-based system-wide scheduler that integrates a Selective File Preloader, an Adaptive Memory Reclaimer, and a Context-Aware Process Killer. Implemented across the Android framework and Linux kernel without app changes, AppFlow cuts GB-scale cold-launch latency by 66.5\% (e.g., 2s$\rightarrow$690ms) and sustains 95\% of launches within 1s over a 100-day test, significantly improving responsiveness and multitasking experience.