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Summary: Minimizing the Flow Time without Migration
Baruch Awerbuch \Lambda Yossi Azar y Stefano Leonardi z Oded Regev x
Abstract
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 algo
rithm, both in offline and online settings, can be signifi
cantly 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 case of a single
processor, most operating systems can easily handle pre
emptions, 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 online or offline setting.
Leonardi and Raz (STOC'97) showed that the well
known algorithm, shortest remaining processing time
(SRPT), performs within a logarithmic factor of the opti
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