Efficient quality of service support within endsystems for high speed multimedia networking
Raman Gopalakrishna · 1997
This dissertation describes the design and implementation of a framework for providing quality-of-service (QoS) guarantees within endsystems for high speed networking and multimedia applications. There are four components in this framework-QoS specification, QoS mapping, QoS enforcement, and protocol implementation with QoS guarantees. Our QoS specification scheme identifies a set of application classes and their QoS parameters that can express the communication requirements of most applications. From the QoS specifications, QoS mapping operations derive resource requirements for each application stream. Important resources that we consider are the CPU and the network connection. QoS enforcement focuses on efficient operating system mechanisms to provide real-time guarantees for protocol and application processing. We describe the design and implementation of a real-time concurrency mechanism called the real-time upcall (scRTU) to provide processing guarantees, and to efficiently implement protocols in user space with QoS guarantees. We also develop a methodology to analyze a number of practical real-time scheduling algorithms that can be used to schedule scRTUs. Finally, we describe how the scRTU mechanism can be used to implement protocols in user space with QoS guarantees. We have developed a number of techniques for improving the efficiency of user space protocols, and demonstrated their effectiveness in the context of an scRTU based implementation of the scTCP/IP protocol suite. The novel aspect of our implementation is the close integration of protocol processing and scheduling. This results in very efficient protocol implementations. It also allows guaranteed bandwidth and low delay streams to coexist simultaneously within the endsystem and to obtain predictable performance.