RMDP--A Real-time CPU Scheduling Algorithm to Provide QoS Guarantees for Protocol Processing

Abstract

We present the analysis of a real-time CPU scheduling algorithm specifically designed to provide processing guarantees for multimedia applications. It is motivated by the need to reduce the number of context switch operations in protocol processing while being able to provide bandwidth and delay guarantees to each protocol session. We have implemented this scheme in the NetBSD operating system. Our experimental and simulation results show that there is substantial reduction in the number of context switch operations. We present the scheme and derive its schedulability test. 1 Introduction One of the basic algorithms for real-time scheduling is the rate monotonic(rm) [3] scheme. rm is fully preemptive i.e. a running thread is pre-empted as soon as a higher priority thread becomes runnable. However, pre-emptions can cause context switching which is an expensive operation in most operating systems. We present a modified scheme called rate monotonic with delayed pre-emption(rmdp) in whic..