  Discriminatory Processor Sharing policy introduced by Kleinrock is of a great
interest in many application areas, including telecommunications, web
applications and TCP flow modelling. Under the DPS policy the job priority is
controlled by the vector of weights. Verifying the vector of weights it is
possible to modify the service rates of the jobs and optimize system
characteristics. In the present paper we present the results concerning the
comparison of two DPS policies with different weight vectors. We show the
monotonicity of the expected sojourn time of the system depending on the weight
vector under certain condition on the system. Namely, the system has to consist
of classes with means which are quite different from each other. The classes
with similar means can be organized together and considered as one class, so
the given restriction can be overcame.
