Abstract

MULLER, Felipe Martins  and  LIMBERGER, Sergio João. Uma heurística de trocas para o problema de sequenciamento de tarefas em processadores uniformes. Pesqui. Oper. [online]. 2000, vol.20, n.1, pp. 31-42. ISSN 0101-7438.  http://dx.doi.org/10.1590/S0101-74382000000100005.

This paper examines the nonpreemptive assignment of independent jobs to a system of uniform processors with the objective of reducing makespan, or the time required from the start of execution until all jobs are completed. We consider a set of n jobs, each having an execution time and a set of m³2 processors which are assumed to have different speeds (say s1 = 1£s₂£ ... £s_m). Since the problem of finding a minimal makespan has been show to be NP-hard, we develop a powerful interchange heuristic. The heuristic proposed is composed by three phases: initial assignment, job reassignment and job interchange. The main feature of this method is not perform a pre-classification of the tasks. Some comparison are made with other heuristic schemes and a lower bound that validates the results obtained. The heuristic achieve optimal solutions for several instances in a short computational time.

Keywords : scheduling problems; combinatorial optimization; heuristics.