A Unifying Approach to Scheduling
This paper presents a scheme for classifying
scheduling algorithms based on an abstract model 
of a scheduling system which formalizes the notion of
priority.  Various classes of scheduling algorithms
are defined and related to existing algorithms.  A
criterion for the implementation efficiency of an 
algorithm is developed and results in the definition
of time-invariant algorithms, which include most 
of the commonly implemented ones.  For time-invariant
algorithms, the dependence of processing rates 
on priorities is derived.  The abstract model provides
a framework for implementing flexible schedulers 
in real operating systems.  The policy-driven scheduler
of Bernstein and Sharp is discussed as an example 
of such an implementation
CACM July, 1977
Ruschitzka, M.
Fabry, R. S.
