The Effect of Message-Class Dependent Threshold-Type Scheduling on the Delay for the M/M/n Queue

Iwao SASASE  Yoshifumi NISHIO  Hitomi NAKAMURA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E75-A   No.9   pp.1087-1099
Publication Date: 1992/09/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Information Theory and Its Applications)
M/M/n queue,  threshold-type scheduling,  queueing delay,  resequencing delay,  

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The effect of mesage-class dependent threshold-type scheduling on queueing delay and resequencing delay for the M/M/n queueing system is analyzed. We first derive the expressions for the state transition equations, mean queueing delay, resequencing delay and total delay for the M/M/n queueing system shared by C different message classes under a threshold-type scheduling in which the threshold values depend on the message class at the head of queue and the number of messages in the buffer. Next, the numerical calculation and the computer simulation are carried out for the queueing system with two servers. It is found that the message-class dependent threshold-type scheduling is effective to reduce the resequencing delay of some specific message class, which can not be attained under the conventional threshold-type scheduling, and thus, the proposed scheduling can satisfy the different requirements of the different message classes, such as minimizing only queueing delay or total delay including resequencing delay.