Abstract
Two well known algorithms for real-time scheduling are the Least Laxity First (LLF) algorithm and the Earliest Deadline First (EDF) algorithm. The EDF algorithm always runs the jobs with earliest deadline. The LLF algorithm always runs the jobs with least laxity; the laxity of a job is its deadline minus the sum of its remaining processing time and the current time. In the paper [1], it was claimed that every instance schedulable by EDF on m processors is also schedulable by LLF on m processors. We show that this claim is, in fact, incorrect. We give an instance I DfJ1; J2; J3; J4; J5; J6g, such that EDF completes all jobs in I by their deadline on two processors, while LLF does not complete every job in I by its deadline on two processors. We use the notation JiD.ri; xi; di/ to denote that the arrival time of the job Ji is ri , the length of the job Ji is xi , and the deadline of the job Ji is di . The instance I is then
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
