Full virtualization on low-end hardware: a case study

Abstract

Most hypervisors today rely either on (1) full virtualization on high-end hardware (i.e., hardware with virtualization extensions), (2) paravirtualization, or (3) both. These, however, do not fulfill embedded systems' requirements, or require legacy software to be modified. Full virtualization on low-end hardware (i.e., hardware without virtualization extensions), on the other end, has none of those disadvantages. However, it is often claimed that it is not feasible due to an unacceptably high virtualization overhead. We were, nevertheless, unable to find real-world quantitative results supporting those claims. In this paper, performance and footprint measurements from a case study on low-end hardware full virtualization for embedded applications are presented. More specifically, this paper presents: (1) an evaluation of the virtualization overhead in a Linux-based system as a guest on POK/rodosvisor, a real time operating system for embedded systems featuring low-end hardware full virtualization; (2) a detailed look at the performance of POK/rodosvisor's internal operation, namely, interrupt handlers and context switching; and (3) POK/rodosvisor's footprint for various configurations. To the best of our knowledge, this is the first paper ever to present performance measurements about a Linux-based system as a guest on a hypervisor based on low-end hardware full virtualization, and therefore, targeting a common real-world scenario.