Azalea-Unikernel: Unikernel into Multi-kernel Operating System for Manycore Systems

As applications such as a big data processing require more CPUs, manycore systems with a large number of CPUs have been developed to meet this requirement. However, without the in-depth consideration of parallelism, only increasing the number of cores cannot provide performance scalability. Furthermore, the current monolithic operating systems (e.g., Linux) cannot also provide performance scalability in manycore systems due to the cache coherency of shared data problems. As a result, multi-kernel operating systems have emerged as an alternative solution for scalability in manycore systems. We have developed a multi-kernel operating system called Azalea, which consists of a full-weight kernel (FWK) and lightweight kernel (LWK). The FWK handles heavy kernel services (i.e., file system services), and the LWK supports the minimal kernel functions as much as needed of application execution and eliminates the sharing of kernel data. However, there remain kernel noises in LWK such as context switching and page fault handling, even though they are less than Linux. In this paper, we propose Azalea-unikernel, which applies unikernel techniques into the LWK to reduce kernel noises. It eliminates privilege switching and address space switching by integrating user-kernel-address space. In particular case, the azalea-unikernel shows 7.5× better performance than LWK and Linux.