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Scheduling: Proportional Share In this chapter, we'll examine a different type of scheduler known
 

Summary: 9
Scheduling: Proportional Share
In this chapter, we'll examine a different type of scheduler known
as a proportional-share scheduler, also sometimes referred to
as a fair-share scheduler. Proportional-share is based around
a simple concept: instead of optimizing for turnaround or re-
sponse time, a scheduler might instead try to simply guarantee
that each job obtain a certain percentage of CPU time.
An excellent modern example of proportional-share schedul-
ing is found in research by Waldspurger and Weihl [WW94],
and is known as lottery scheduling; however, the idea is cer-
tainly much older []. The basic idea is quite simple: every so
often, hold a lottery to determine which process should get to
run next; processes that should run more often should be given
chances to win the lottery. Easy, no? Now, onto the details!
9.1 Basic Concept: Tickets Represent Your Share
Underlying lottery scheduling is one very basic concept: tick-
ets, which are used to represent the share of a resource that a
process (or user or whatever) should receive. The percent of
tickets that a process has represents its share of the system re-

  

Source: Arpaci-Dusseau, Remzi - Department of Computer Sciences, Department of Computer Sciences, University of Wisconsin at Madison

 

Collections: Computer Technologies and Information Sciences