A loop-free asynchronous data sharing mechanism in multiprocessor real-time systems based on timing properties

This paper presents an asynchronous data sharing mechanism for real-time applications with multiple writers. The mechanism is constructed from a fully asynchronous single writer data sharing mechanism implemented through a timing-based approach, which, being lock-free and loop-free, addresses the problems of priority inversion and unbounded blocking among real-time tasks running under priority-based scheduling. By replicating the single writer data sharing mechanism and modifying its data buffer access control function, the multi-writer data sharing mechanism is constructed such that the desired safety property and feasibility conditions on data buffer allocation are maintained by those single writer data sharing mechanisms. To address the issue on data coherence, all the writer tasks follow a data coherence protocol which is designed with the concept of timestamp ordering. The feasibility condition of this protocol is constructed through analyzing the timing properties of writer tasks. This multi-writer data sharing mechanism stands for another demonstration of the timing-based approach which is an effective alternative to the traditional algorithm-based approaches.