摘要
A multi-class macro-scheduler is described in this paper. The scheduler periodicaily determines the number of jobs from each class that should be activated to minircdze a weighted som of the mean system residence time without satvrating the .systern. The compatation is based on the estimated system workload in the next interval. Thus it is adaptive to workload variation. The service provided to each class (specifically, the mean response time) may be adjusted by changing the weight associated with the job class. The schere is based on. mathematical modelling. The solution is obtained through the use of queuing theory, operational analysis and optimization theory. Exponential smoothing techniqne is employed to reduce the error of estimating the value of the model pararneters. Simulation resuflts show the scheme to be both stable and robust. Performanee iutprovemeat over some of the eristing schemes (the 50%, L=S and the Knee criteria) is significant under some workloads. The overhead involved in its implementation is aoceptable and the errors due to some of the assumptions used in the formalation and solution of the model are discussed.
