© 1989 by British Computer Society
Priority Semaphores
¶1 Fachbereich Informatik, Technische Hochschule Darmstadt, Alexanderstr. 24, D-6100 Darmstadt, Germany, 2 Department of Computer Science, University of Newcastle, NSW 2308, Australia
Neither low-level mechanisms such as semaphores nor higher-level mechanisms such as path expressions provide a simple means of solving synchronisation problems involving the scheduling of processes or classes of processes according to different priorities. This paper presents a new set of primitives which are easy to use and simple to implement. Their use is described in terms of the familiar readerwriter problem and the general scheduling problem involving arbitrary levels of priority with support for pre-emption and shared access by certain process classes. An efficient implementation, which reduces to a minimum the number of calls required to the process scheduler, is then described.
Received May 1987.
* Fachbereich Informatik, Technische Hochschule Darmstadt, Alexanderstr. 24, D-6100 Darmstadt, F.R.G.
Department of Computer Science, University of Newcastle, NSW 2308, Australia