Application performance and flexibility on exokernel systems

Abstract

The exokemel operating system architecture safely gives untrusted software efficient control over hardware and software resources by separating management from protection. This paper describes an exokemel system that allows specialized applications to achieve high performance without sacrificing the performance of unmodified UNIX programs. It evaluates the exokemel architecture by measuring end-to-end application performance on Xok, an exokernel for Intel x86-based computers, and by comparing Xok's performance to the performance of two widely-used 4.4BSD UNIX systems (FreeBSD and OpenBSD). The results show that common unmodified UNIX applications can enjoy the benefits of exokernels: applications either perform comparably on Xok/ExOS and the BSD UNIXes, or perform significantly better. In addition, the results show that customized applications can benefit substantially from control over their resources (e.g., a factor of eight for a Web server). This paper also describes insights about the exokemel approach gained through building three different exokemel systems, and presents novel approaches to resource multiplexing.