The Design of a QoS-Controlled ATM-Based Communications System in Chorus

We describe the design of an application platform able to run distributed real-time and multimedia applications alongside conventional UNIX programs. The platform is embedded in a micro-kernel/ PC environment and supported by an ATM based, QoS driven communications stack. We focus in particular on resource management aspects of the design and deal with CPU scheduling, network resource management and memory management issues. An architecture is presented which guarantees QoS levels of both communications and processing with varying degrees of commitment as specified by user level QoS parameters. The architecture uses admission tests to determine whether or not new activities can be accepted and includes modules to translate user level QoS parameters into representations usable by the scheduling, network and memory management subsystems.