Design of a distributed operating system for ada(registered trademark) (rendezvous, programming, computers)
Jr. Richard Miller Weatherly · 1984
The full potential of the Ada('(REGTM)) programming language will not be utilized until the mapping of individual tasks onto distinct physical processors is achieved. This research takes steps toward that end by proposing a network operating system to support distributed Ada tasking. The operating system is a collection of identical kernels where each kernel is in control of a processor in the network. A minimum set of monitors were chosen as the interface between the tasks and the kernels that support them. Nine monitor services were found to be sufficient to handle the Ada task dynamics and inter-task rendezvous. Given that monitors look like normal procedures to the user and that most languages support procedure calls, the monitor approach can be extended to other language systems. The kernel, which contains the monitor algorithms, communicates with the other kernels in the network through message passing. Messages are of twelve fixed classes and can carry all the information needed to communicate during rendezvous and to maintain the hierarchical relationship between tasks. A model was constructed, in Ada, that allowed the behavior of a kernel to be studied while various scenarios were played out between simulated tasks. In addition to functional verification, performance analysis was conducted that showed no worse than a linear relationship between the number of tasks on a given processor and the overhead time required by its kernel. ('(REGTM))Ada is a registered trademark of the U.S. Government, Ada Joint Project Office.