Evaluation of Dynamic Running Mode Switch Mechanism by Presence of OS Protection

System call is high-cost operation because it causes switch the running mode of a process. As a solution reduce overhead of system call, we have proposed the Dynamic running Mode Switch Mechanism (DMSM) which can switch the running mode of process dynamically. Because DMSM enables that system call is substituted by simple function call, it dramatically improved of overhead of system call. However, DMSM cannot protect the OS to access an applications program executing by supervisor-mode. In this paper, we propose protection function of OS from an application with a supervisor-mode. We propose two types of protection function, i.e., virtual space switch mechanism and segmentation switch mechanism. We also evaluate the effectiveness of two protection functions compared with original DMSM.