Set Of Real-time Tasks Research Articles

Modeling and validation of the real-time Mach scheduler

Real-time scheduling theory is designed to provide a priori verification that all real-time tasks meet their timing requirements. However, this body of theory generally assumes that resources are instantaneously pre-emptable and ignores the costs of systems services. In previous work [1, 2] we provided a theoretical foundation for including the costs of the operating system scheduler in the real-time scheduling framework. In this paper, we apply that theory to the Real-Time (RT) Mach scheduler. We describe a methodology for measuring the components of the RT Mach scheduler in user space. We analyze the predicted performance of different real-time task sets on the target system using the scheduling model and the measured characteristics. We then verify the model experimentally by measuring the performance of the real-time task sets, consisting of RT Mach threads, on the target system, The experimental measurements verify the analytical model to within a small percentage of error. Thus, using the model we have successfully predicted the performance of real-time task sets using system services, and developed consistent methodologies to accomplish that prediction.

A theory for the initial allocating of real time tasks in distributed systems

Referring to a set of real time tasks with arriving time, executing time and deadline, this paper discusses the problem of polynomial time initial-allocating approximation algorithms in a distributed system and five new results are gained which provide a theory for the designing of initial-allocating algorithms of real time tasks.

On-line scheduling of real-time tasks

An optimal on-line scheduler is given for a set of real-time tasks with one common deadline on m processors. It is shown that no optimal scheduler can exist for tasks with two distinct deadlines. Finally, an optimal on-line scheduler is given for situations where processors can go down unexpectedly. >