Implementation and Evaluation of the Synchronization Protocol Immediate Priority Ceiling in PREEMPT-RT Linux

In general purpose operating systems, such as the mainline Linux, priority inversions occur frequently and are not considered harmful. They are not avoided or limited as in real-time systems. In the current version of the kernel PREEMPT-RT Linux, the protocol used for priority inversion control is the Priority Inheritance. The objective of this paper is to propose the implementation of an alternative protocol, the Immediate Priority Ceiling, for use in drivers dedicated to real-time applications. This paper explains how the protocol was implemented in the real-time kernel and compare the protocol implemented with the Priority Inheritance implementation, currently used in the real-time kernel.