SRPT optimally utilizes faster machines to minimize flow time
SODA '04 Proceedings of the fifteenth annual ACM-SIAM symposium on Discrete algorithms
Scheduling against an adversarial network
Proceedings of the sixteenth annual ACM symposium on Parallelism in algorithms and architectures
Nonclairvoyant scheduling to minimize the total flow time on single and parallel machines
Journal of the ACM (JACM)
Approximating total flow time on parallel machines
Journal of Computer and System Sciences
Competitive non-migratory scheduling for flow time and energy
Proceedings of the twentieth annual symposium on Parallelism in algorithms and architectures
SRPT optimally utilizes faster machines to minimize flow time
ACM Transactions on Algorithms (TALG)
Proceedings of the forty-first annual ACM symposium on Theory of computing
Review: Task assignment policies in distributed server systems: A survey
Journal of Network and Computer Applications
An online scalable algorithm for minimizing lk-norms of weighted flow time on unrelated machines
Proceedings of the twenty-second annual ACM-SIAM symposium on Discrete Algorithms
Online scheduling on identical machines using SRPT
Proceedings of the twenty-second annual ACM-SIAM symposium on Discrete Algorithms
Improved multi-processor scheduling for flow time and energy
Journal of Scheduling
Reallocation problems in scheduling
Proceedings of the twenty-fifth annual ACM symposium on Parallelism in algorithms and architectures
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We consider the classical problem of scheduling jobs in a multiprocessor setting in order to minimize the flow time (total time in the system). The performance of the algorithm, both in offline and online settings, can be significantly improved if we allow preemption, i.e., interrupt a job and later continue its execution, perhaps migrating it to a different machine. Preemption is inherent to make a scheduling algorithm efficient. While in the case of a single processor most operating systems can easily handle preemptions, migrating a job to a different machine results in a huge overhead. Thus, it is not commonly used in most multiprocessor operating systems. The natural question is whether migration is an inherent component for an efficient scheduling algorithm in either the online or offline setting.Leonardi and Raz [Proceedings of the Twenty-Ninth Annual ACM Symposium on Theory of Computing, El Paso, TX, 1997, pp. 110--119] showed that the well-known algorithm, shortest remaining processing time (SRPT), performs within a logarithmic factor of the optimal offline algorithm. Note that SRPT must use both preemption and migration to schedule the jobs. It is not known if better approximation factors can be reached and thus SRPT, although it is an online algorithm, becomes the best known algorithm in the offline setting. In fact, in the online setting, Leonardi and Raz showed that no algorithm can achieve a better bound.Without migration, no (offline or online) approximations are known. This paper introduces a new algorithm that does not use migration, works online, and is just as effective (in terms of approximation ratio) as the best known offline algorithm that uses migration.