A kernel thread running on the outside of the kernel and its implementation

摘要

In this paper, the authors propose a kernel-mode thread that runs independently of the kernel and external to the operating system, then discuss its implementation and scope of application. Using a test system running FreeBSD 2.2.5 on an IBM PC, the authors were able to create a new thread that had virtually no impact on the Unix system. This external thread and the Unix system are executed via the meta-scheduler using round-robin scheduling that allows for CPU preemption. The external thread runs over an interval of several tens of milliseconds, that is periodically in real time. In addition, by making a few changes to the Unix kernel, this interval can be reduced to 1 millisecond, and so can be used for continuous multimedia processing and robot control. This system is superior in terms of how it acquires control from the Unix system. Because control is acquired using the kernel function timeout(), programming the external thread is easier to do compared to other systems. Using this system, the authors created a system that visualizes the states of memory maps for designated processes and periodic monitoring of Unix process states. The system operates reliably, and in the future the authors plan to evaluate various uses for it.