The priority ceiling protocol is a new technique that addresses the priority inversion problem, i.e., the possibility that a high-priority task can be delayed by a low-priority task. Under the priority ceiling protocol, a high priority task can be blocked at most once by a lower priority task. This paper defines how to apply the protocol to ADA. In particular, restrictions on the use of task priorities in ADA are defined as well as restrictions on the use of ADA tasking constructs. An extensive example illustrating the behavior guaranteed by the protocol is given.
This paper was presented at the 2nd International Workshop on Real-Time ADA Issues in May 1988.