Operational Analysis of Queueing Networks

In typical validations of computer performance models, analysist interpret the ptja) of queueing networks as time-proportions during which a given network state n is observed. They parameterize performance calculations with directly measured device service time functions and job device visit counts. Three operational assumptions constitute a minimal set of assumptions for calculating these p(n): the number of jobs observed to arrive at a device is (almost) the same as the number observed to depart; the number of transitions into a given system state is (almost) the same as the number out; arid the on-line service functions of devices are the same as the off-line service functions. The last assumption, called "homogeneity", is the major approximation, on account of which queueing network results are not exact. It is closely related to the principle of decomposability* Operational queueing network theory is weaker than Markovian queueing network theory. (1) Supported in part by NSF Grant GJ-41289 at Purdue University. (2) Con^uter Sciences Dept., Purdue University, W. Lafayette, IN 47907 USA. (3 ) BGS Systems, Inc . , Box 128, Lincoln, MA 01773 USA.