Analyzing and Modeling Device Specific I/O Performance Behavior in Smartphone Flash Memory

Abstract

Flash memory, widely used in smartphones, exhibits complex and sometimes unpredictable performance characteristics. This study investigates the device specific performance behavior of synchronous write operations on flash memory in smartphones, and reveals that some flash memory devices undergo periodic and significant write performance degradation, where the completion time can increase by more than tenfold. Our analysis is based on detailed measurements from a Pixel 3a smartphone. We then demonstrate that its occurrence depends on the I/O block size and whether data is written to previously written or unwritten areas. Based on these observations, we propose a prediction method that estimates the timing of the next degradation based on the device-specific periodic interval observed in our measurements. Finally, we introduce a practical mitigation technique: a dummy write operation that preemptively absorbs the impact of the upcoming degradation, thereby stabilizing performance. Our findings provide both a deeper understanding of flash memory behavior and a foundation for improving user-perceived system stability.