Implementing execution-time clocks for the Ada Ravenscar profile

The capability to monitor the amount of processor time that is used by real-time tasks is crucial for building real-time systems that are robust with respect to worst case execution time estimations. Execution-time clocks and timers have been proposed to be added to the language in order to support this functionality. Since a wide class of systems which may benefit from this mechanism are likely to use the Ada tasking subset known as the Ravenscar profile, it is important to check that the proposed execution-time clocks can be implemented on top of the simplified run-time systems that are used to support this profile. This paper describes a pilot implementation of execution-time clocks for the ORK kernel, and gives some examples of their possible usage in Ravenscar programs.