A capacity sharing and stealing strategy for open real-time systems

Nogueira, Luís; Pinho, Luís Miguel

http://hdl.handle.net/10400.22/3848

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Authors

Nogueira, Luís

Pinho, Luís Miguel

Abstract(s)

This paper focuses on the scheduling of tasks with hard and soft real-time constraints in open and dynamic real-time systems. It starts by presenting a capacity sharing and stealing (CSS) strategy that supports the coexistence of guaranteed and non-guaranteed bandwidth servers to efficiently handle soft-tasks’ overloads by making additional capacity available from two sources: (i) reclaiming unused reserved capacity when jobs complete in less than their budgeted execution time and (ii) stealing reserved capacity from inactive non-isolated servers used to schedule best-effort jobs. CSS is then combined with the concept of bandwidth inheritance to efficiently exchange reserved bandwidth among sets of inter-dependent tasks which share resources and exhibit precedence constraints, assuming no previous information on critical sections and computation times is available. The proposed Capacity Exchange Protocol (CXP) has a better performance and a lower overhead when compared against other available solutions and introduces a novel approach to integrate precedence constraints among tasks of open real-time systems.

Keywords

Open real-time systems Dynamic scheduling Resource reservation Residual capacity reclaiming Reserved capacity stealing Shared resources Precedence constraints