基于混合服务策略轮询系统的性能分析

周期轮询系统已被广泛运用于各个领域,如计算机网络、工业制造系统等。在周期轮询系统中,最基本的队列调度策略有门限服务、限定服务以及完全服务。这些调度策略各有其优缺点,文章提出了一种基于混合服务的调度策略,对一些队列采用门限服务,对另一些队列采用限定服务,这样既可以避免在单一的完全服务中低优先级队列有可能出现的队列饥饿现象,又可以对不同的队列提供不同的服务质量。该文通过嵌入马尔可夫链和概率母函数的方法对基于混合服务的轮询系统进行分析,推导出队列的平均队长,并与采用门限服务的轮询系统进行比较,从而说明混合服务系统的优点。

Analysis on Polling System with Mixed Service

Polling systems are used to several application areas including computer networks,the manufacturing system and so on.Limited,gated and exhaustive service disciplines are the basis for a class of queue scheduling policies used in the polling systems and each of them has its advantage and disadvantage.This paper provides a mixed service polling system in which some queues adopt gated service discipline and the others carry out Limited-1service.The properties of this system are:it can prevent queue from resource starvation,and it can provide different QoS guarantee to queue with different service policy.By means of embedded Markov chain and probability generating function,this pa-per discusses and analyzes the mixed service polling system,and obtains the expression of average length.At last by comparing with the performance of gated service polling system,the benefit of the mixed service system is shown.