Rate-based QoS control of multiple flows over a real-time OS

When multiple flows including continuous media streams are simultaneously sent from a computer, allocation, and management of both processor capacity and network bandwidth need to be considered. We propose a framework of Quality of Service (QoS) management inside a sending host that controls execution of sending threads in consideration of utilization of processor capacity and network bandwidth. To distinguish from flows which require only best effort service, we call a flow which requires a specific rate of service "reserved flow". To guarantee QoS of such reserved flow both in processor- and network-intensive cases in a sending host, processor capacity reserve is allocated such that the rate of each reserved flow is attained and non conforming data are policed before they are transmitted. Processor Capacity Manager and the network device driver exchange information in a cooperative manner to support the rate adaptive allocation of processor capacity reserve. We describe design and implementation of our framework on RT-Mach. The results of performance evaluations demonstrate that our scheme performs well for full-duplex Ethernet.