Design and Implementation of A Real-Time Environment on Mach Microkernel

• Main Authors: Tseng,Chih-Chang, 曾智昌
• Other Authors: Juang,Jie-Yong
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/60378572047317114131

碩士 === 國立臺灣大學 === 資訊工程研究所 === 82 === For real-time computing, real-time threads and general threads are treated differently in most operating systems. A real-time thread must have a higher priority and a different scheduling policy comparing with a general thread. Besides, the timing attributes of real-time threads are very important. A real-time environment must support periodical scheduling. The ordinary mutual exclusion mechanism will cause a priority inver- sion problem, which may result in an unbounded delay for a high priority thread. Remote procedure call (RPC) also presents a problem. In Mach, Mach Interface Generator(MIG) generates RPC stubs, and the RPC operation is achieved by message passing. This causes priority inversion problems. Consequently, real- time threads will be delayed by server threads due to their low priority. We implemented a real-time thread package for users to devel- op real-time applications. This package supports real- time thread management, periodical scheduling, and the management of priori- ties and scheduling policies. To solve the problem of priority inversion in RPC, we propose a mechanism of priority hand-out between client threads and server threads. The server thread inherits the client thread's priority during serving the client thread. Moreover, we also implemented a tool to generate these RPC code. Benchmark results show that this environment is more pre- dictable than original C Threads and MIG environment on Mach. It provides better opportunities for real-time applications to meet their deadlines.