The Power of Reordering for Online Minimum Makespan Scheduling

In the classic minimum makespan scheduling problem, we are given an input sequence of jobs with processing times. A scheduling algorithm has to assign the jobs to m parallel machines. The objective is to minimize the makespan, which is the time it takes until all jobs are processed. In this paper, we consider online scheduling algorithms without preemption. However, we do not require that each arriving job has to be assigned immediately to one of the machines. A reordering buffer with limited storage capacity can be used to reorder the input sequence in a restricted fashion so as to schedule the jobs with a smaller makespan. This is a natural extension of lookahead. We present an extensive study of the power and limits of online reordering for minimum makespan scheduling. As main result, we give, for m identical machines, tight and, in comparison to the problem without reordering, much improved bounds on the competitive ratio for minimum makespan scheduling with reordering buffers. De...

• Type: Conference
• Year: 2008
• Where: FOCS
• Authors: Matthias Englert, Deniz Özmen, Matthias Westermann
• Keywords: FOCS 2008, Input Sequence, Minimum Makespan Scheduling, Scheduling Algorithms, Theoretical Computer Science