Priority Inheritance Revisited. Towards the conformance of real-time protocols

Abstract

The priority inversion problem was discovered in the eighties. The decisive ideas to cope with this problem have been published in the nineties. In the meantime the suppliers of real-time operating systems and run-time systems have occupied this topic by providing certain protocols in order to give the application programmer comfortable system calls to avoid priority inversion. At a closer look there are considerable errors and defects in the protocol implementations but also in the approach to derive these protocols. So, on the one hand this article unfolds an undetected error of the priority inheritance protocol. On the other hand it shows by a sequence of test suites that certain operating systems and runtime systems have different kinds of defects in implementing the protocol.