Delegating the kernel functions to an application program in UV6

While processor cores available on a single system gradually but steadily increase every year, they are extremely underutilized except for well configured servers. The existence of such surplus processors can impact the operating system (OS) design and organization. We would like to use those processors to change the OS organization in order to increase the productivity of the OS kernel code by delegating the kernel functions to an application program. We designed and implemented UV6, of which kernel runs as an application program and manages a real processor with its native interface. The experiment results running micro benchmark programs show that 1) the frequently used simple kernel functions can perform comparably by leaving them in the proxy kernel, 2) a communication cost between the UV6 application kernel and its user process is negligible, and 3) there are cases where UV6 outperforms the original XV6. We also showed the acceleration of the UV6 kernel is possible by utilizing a SIMD unit of a processor.