Hierarchical QoS management for time sensitive applications

The use of real time techniques in new application fields such as multimedia computing, has extended classical algorithms to more dynamic environments, introducing the problem of controlling and adapting the quality of service provided by an application. The authors investigate the possibility of integrating application-dependent adaptation strategies with reservation techniques for handling multimedia real time applications. We show how a global adaptive reservation mechanism can be combined with a local application-level adaptation, obtaining a hierarchical management scheme. The need for the two forms of adaptation (application dependent and global) and the effectiveness of the proposed hierarchical scheme are shown by a set of experiments on multimedia applications. All the experiments have been performed by running the real applications on a real time kernel.