A Fully Asynchronous Reader/Writer Mechanism for Multiprocessor Real-Time Systems

Data sharing among tasks within multiprocessor real-time systems is a crucial issue. This report presents a fully asynchronous mechanism of sharing data between a single writer and multiple readers. The writer and all the readers are allowed to access the shared data asynchronously in a loop-free and wait-free manner because neither locking operations nor repeated actions of read-and-check are involved. Its implementation uses only (n + 2) buffer slots for n readers, and employs an atomic `Store-IfZero ' operation which can be easily simulated with the Compare-and-Swap instruction. Since neither writing nor reading the shared data imposes any effect upon other tasks in the system, this mechanism introduces no impact upon the timing behaviour of tasks. When employed by real-time applications, it helps to reduce blocking and priority inversion problems incurred by the commonly used lock-based synchronization mechanisms. 1 Introduction Data sharing is a basic approach to achieving inter..