Deadline Missing Prediction Through the Use of Milestones

Distributed Real-Time Thread is an important concept for distributed real-time systems. Distributed Threads are schedulable entities with an end-to-end deadline that transpose nodes, carrying their scheduling context. In each node, the thread will be locally scheduled according to a local deadline, which is defined by a deadline partitioning algorithm. Mechanisms for predicting the missing of deadlines are fundamental if corrective actions are incorporated for improving system quality of service. In this work, a mechanism for predicting missing deadlines is proposed and evaluated through simulation. In order to illustrate the main characteristics of the proposed mechanism, experiments will be presented taking into account different scenarios of normal load and overload. Simulations show that the deadline missing prediction mechanism proposed presents good results for improving the overall performance and availability of distributed systems

A Robust Adaptive Metric for Deadline Assignment in Heterogeneous Distributed Real-Time Systems

In a real-time system, tasks are constrained by global endto -end (E-T-E) deadlines. In order to cater for high task schedulability, these deadlines must be distributed over component tasks in an intelligent way. In this paper, we present an improved version of the slicing technique and extend it to heterogeneous distributed hard real-time systems. The salient feature of the new technique is that it utilizes adaptive metrics for assigning local task deadlines. Using experimental results we show that the new technique exhibits superior performance with respect to the success ratio of a heuristic scheduling algorithm. For smaller systems, the new adaptive metric outperforms a previously-proposed adaptive metric by 300%, and existing non-adaptive metrics by more than an order of magnitude. In addition, the new technique is shown to be extremely robust for various system configurations. 1 Introduction In a distributed real-time computing system, applications are decomposed into tasks, wh..