Optimized Design of Filesystems for Unikernel

Kyeong Woon Cho, Hyo Kyeong Ban

http://doi.org/10.5626/JOK.2024.51.5.389

Unikernel is a special-purpose kernel optimized for single applications and services. Compared to general-purpose kernels, its advantages include fast boot time, small memory footprint, high performance, and security. Unikernel applications attempt to maintain compatibility with the runtime environment of the general-purpose kernel and are used in binary or source-compatible form with legacy applications. Most existing unikernel projects implemented filesystem APIs with a priority on running applications rather than performance optimizations. Accordingly, it is a common practice to deploy a general-purpose file system naively or to introduce a host filesystem dependent method. In this paper, we discuss the design of unikernel file systems taking into account the purpose of unikernel, i.e., ensuring optimized performance with minimal system resources while maintaining security. Specifically, we analyze the performance and memory requirements for file systems supported by major unikernels through micro-benchmarks and suggest file system design guidelines to provide optimized performance and security.