Analyses of the Memory Usage Efficiency of the Scudo Memory Allocator

KyungSeok Lee, Taehyung Lee, Young Ik Eom

http://doi.org/10.5626/JOK.2023.50.2.103

Optimizing memory usage is important in mobile systems because diverse applications share limited system memory in those systems. Although the default memory allocator of Android, Scudo, is designed to mitigate vulnerabilities related to heap memory and optimize the memory allocation performance, it has inefficiency in terms of memory usage aspects. This paper addresses two problems based on the structure and operation mechanism of Scudo. First, the problems that occur due to the static number of local caches are analyzed. Second, the internal fragmentation problems induced by the inefficient free-chunk management policy are analyzed. The evaluation results show that, according to the characteristics of applications, there are some performance overheads and memory waste due to the static number of local caches in Android systems. Furthermore, we confirm that repeated allocation and free operations fragment almost all allocated physical pages in Scudo; hence pages are not actively reclaimed to the OS even after 90% of allocated chunks are freed.