An Improved Priority Inheritance Protocol and Its Algorithm

Priority reverse is a kind of phenomenon that the higher priority task is blocked by the lower priority task since they are using the same sources in real time system.Priority reverse makes it is impossible to predict the execution time of the high priority task,and increases the indeterminacy of real time system.Although early priorities solved priority reverse,there are some limitations.To address these limitations,this paper gives rise to an improved priority inheritance protocol.In the improved protocol,the semaphores are acquired according to a fixed predetermined non-revolving sequence to avoid dead lock.Protocol establishes overtime protection mechanism to avoid prolonged block when tasks are acquiring semaphores.It analyzes the property of the protocol,on the bases of which an implementation under Linux is described.Experiment results show this protocol can perform efficiently.