Practical optimization/approximation algorithms are described for scheduling a set of partially ordered computational tasks onto a multiprocessor system so that the schedule length will be minimized. Since this problem belongs to the class of 'strong' NP-hard problems, it is not possible to construct pseudopolynomial time optimization algorithms or fully polynomial time approximation schemes unless P equals NP. A heuristic algorithm named CP/MISF (critical path/most immediate successors first) and an optimization/approximation algorithm named DF/IHS (depth-first/implicit heuristic search) are proposed. DF/IHS is an excellent scheduling method which can reduce markedly space complexity and average computation time by combining the branch-and-bound method with CP/MISF; it allows us to solve very large scale problems with a few hundred tasks. Numerical examples are included to demonstrate the effectiveness of the proposed algorithms.
|Number of pages||7|
|Journal||IEEE Transactions on Computers|
|Publication status||Published - 1984 Nov|
ASJC Scopus subject areas
- Hardware and Architecture
- Electrical and Electronic Engineering