There has been considerable activity in recent years in developing analytical techniques for hard real-time systems. Inevitably these techniques make simplifying assumptions so as to reduce the complexity of the problem to be solved. Unfortunately this leads to a gap between theory and engineering practice. The paper presents new analysis that enables the costs of the scheduler (clock overheads, queue manipulations and release delays) to be factored into the standard equations for calculating worst-case response times. As well as predicting the true behavior of realistic systems, the analysis also allows free parameters, such as clock interrupt rate, to be determined.>

The increasing use of communication networks in time-critical applications presents engineers with fundamental problems with the determination of response times of communicating distributed processes. Although there has been some work on the analysis of communication protocols, most of this is for idealised networks. Experience with single-processor scheduling analysis has shown that models which abstract away from implementation details are at best very pessimistic, and at worst lead to an unschedulable system being deemed schedulable. In this paper, we derive an idealised scheduling analysis for the CAN real-time bus, and then study two actual interface chips to see how the analysis can be applied.>

In this paper we show how existing real-time scheduling theory, developed to analyse the behaviour of tasks executing on processing resources, can be applied to the problem of guaranteeing the performance of multi-media information streams read from a disk system. Analysis is derived that takes into account disk layout and predicts the worst-case response times for disk requests. It is shown how buffer size, priority of request and size of non-pre-emptable operations all crucially affect behaviour. The object of the paper is to define an effective run-time test that can be used to determine if new streams can be accommodated.

This paper addresses the problem of jointly scheduling tasks with both hard and soft time constraints. We present a new analysis which builds upon previous research into slack stealing algorithms. Our analysis determines the maximum processing time which may be stolen from hard deadline periodic or sporadic tasks, without jeopardising their timing constraints. It extends to tasks with characteristics such as synchronization, release jitter and stochastic execution times, as well as forming the basis for a family of optimal and approximate slack stealing algorithms.>

It is noted that in many hard real-time systems, the set of functions that a system is required to provide may change over time. One way of providing this change is to allow currently running hard real-time tasks to be deleted or changed, or new tasks to be added. The authors define this change as a mode change, and seek to guarantee a priori the timing constraints of all tasks across the change from one mode to another. The authors derive a scheduling theory for static priority preemptive scheduling that can be used to make such guarantees. The schedulability test discussed could easily be incorporated into engineering support tools. The authors also discuss some of the approaches that could be taken to extend the analysis to cope with more complex and interesting scheduling problems, and to handle distributed hard real-time systems.>