Distributed Real-time Operating System Research Articles

Prospects for Predictable Dynamic Scheduling in RTDOS

Future dynamic distributed hard real-time systems may control unpredictable environments and will need operating systems that can handle unknown and changing task populations. In this extreme case, not only is task scheduling totally dynamic, but the system's topology and architecture must adapt to unforeseen configurations. This paper addresses the difficult problem of dynamic task scheduling in a Real Time Distributed Operating System (RTDOS). RTDOS is unique because it possesses the potential to map, at execution time, a flexible topology of networked nodes onto a network of tasks. Attempts will be made to characterize the predictable adaptability of the scheduler so as to relax the pre-run-time scheduling requirements for an RTDOS application. A scheduler architecture and dynamic deadline guarantee scheme are presented along with some experimental results.

Predictable distributed dynamic scheduling in RTDOS

Future dynamic distributed hard real-time systems may control unpredictable environments, and will need predictable and flexible runtime systems that can handle unknown and changing task populations. In this extreme case not only is task scheduling dynamic, but the system topology and architecture might be adapted to unforeseen configurations. The paper addresses the difficult problem of dynamic distributed task scheduling. A new predictable dynamic deadline guarantee scheme has been designed and implemented in the authors' real-time distributed operating system (RTDOS). The algorithms have been proven to guarantee task deadlines even during transient overloads. RTDOS is designed to tackle unpredictable and highly dynamic environments; therefore its task model is quite unrestrictive, supporting periodic and aperiodic tasks both with arbitrary release times and deadlines. The authors place no restriction on the inter-arrival times between successive aperiodic task instances. Moreover, their resource scheduling considers precedence constraints, device allocation and communication requirements. As a consequence, the results can be generalised and applied to many real-time domains. Furthermore, the complexity of the authors' schedulability test has been proved to be O(n). A domain-wide scheduler is described, which maintains its predicted maximum response time even when local nodes are under heavy load. Experimental results confirm the proven expectations of our scheduling scheme.

Mission critical operating systems

Part 1 Operating system design concept: the StarLite operating system choices for mission critical computing operating system correctness is a mission critical requirement the ISIS distributed programming toolkit and the meta distributed operating system - a brief overview the structure of the clouds distributed operating system operating system constructs for managing real-time software complexity. Part 2 Real-time operating system: V - a foundation for mission critical distributed systems MARUTI - an environment for hard real-time applications the spring kernel the ARTS kernel - toward predicatable distributed real-time systems DRAGON SLAYER/MELODY - a highly adaptive distributed operating system for mission critical computing a real-time operating system for HARTS imprecise computations SDEX/44 and 43RSS - navy standard operating systems the kernel computational model of the alpha real-time distributed OS the distributed iRMX operating system - a real-time distributed operating system. Part 3 ADA-based real-time systems: understanding ada runtime environments real-time scheduling theory and ada an overview of DARK.