LaOvl: Lifecycle-Aware Overlay File System for Efficient Container I/O in Cloud Computing

Containers have become a critical component of cloud computing, offering lightweight virtualization for flexible deployment, elastic computing, and dynamic migration. However, the widespread adoption of the Overlay File System (OverlayFS) to provide file system services for containers faces significant I/O performance challenges in high-density and high-concurrency environments. The LRU page cache strategy is poorly suited to the memory access patterns of containers, and OverlayFS unnecessarily persists copy-on-write data. Furthermore, concurrent requests from multiple containers for host file system resources cause interference, further degrading performance on public cloud platforms. This paper proposes the Lifecycle-Aware Overlay File System (LaOvl), which leverages OverlayFS's redirection operations to accelerate container I/O in three key stages. LaOvl accurately senses the container lifecycle, enabling pre-loading of the page cache before startup, fine-grained temporary copy-on-write during runtime, and timely recycling of cold memory upon container destruction. Our evaluation, which includes micro-benchmarks and real-world applications, demonstrates that LaOvl significantly optimizes container I/O and achieves $\mathbf{9 5. 4 \%}$ improvement over the original OverlayFS, outperforming state-of-the-art solutions.