Title :
Scheduling distributed real-time tasks in the DGMF model
Author :
Chen, Deji ; Mok, Aloysius K. ; Baruah, Sanjoy
Author_Institution :
Fisher-Rosemount Syst. Inc., Austin, TX, USA
Abstract :
Analytical results on the real-time scheduling of multiprocessor systems have focused on partitioning and distributing the task set for scheduling on identical single processors, with the assumption that all of a task can be executed on any of a pool of identical processors. A distributed system is a set of nodes networked together. Each node may have a different type of processor and performs different functions. In the distributed environment, a real-time task may require processing on multiple nodes. However, all the nodes have to satisfy the time constraints of the task. In this paper, we show that the Liu & Layland (1973) type of classical task models must be extended to handle this type of distributed real-time tasks. We propose a distributed generalized multi-frame (DGMF) task model. The scheduling problem of DGMF tasks can be reduced to that of scheduling generalized multi-frame (GMF) tasks on a single processor. We analyze the fixed-priority scheduling of (D)GMF tasks and prove that the deadline-monotonic priority assignment is not optimal for the general case of frame-wise priority assignment. In the context of relative deadline assignment, we show that there are simple cases for which deadline-monotonic assignment is optimal
Keywords :
concurrency theory; distributed processing; optimisation; processor scheduling; real-time systems; DGMF task model; deadline-monotonic priority assignment; distributed generalized multi-frame model; distributed real-time task scheduling; fixed-priority scheduling; framewise priority assignment; multiprocessor systems; networked nodes; nonidentical single processors; optimality; relative deadline assignment; task set distribution; task set partitioning; Bridges; Computer science; Databases; Delay; Distributed computing; Multiprocessing systems; Network servers; Processor scheduling; Real time systems; Time factors;
Conference_Titel :
Real-Time Technology and Applications Symposium, 2000. RTAS 2000. Proceedings. Sixth IEEE
Conference_Location :
Washington, DC
Print_ISBN :
0-7695-0713-1
DOI :
10.1109/RTTAS.2000.852447