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SUMMARYWe describe experience on design and implementation of an efficient count sort algorithm on Compute Unified Device Architecture graphics processing units. The novelty of this work is twofold. At first, we propose a count sort algorithm for integers that needs no synchronization at its last step and thus, offers superior performance. At second, this work contributes ad hoc techniques for optimizing the performance of the algorithm on Compute Unified Device Architecture-enabled graphics processing units.

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Abstract:The examination timetabling problem belongs to the class of combinatorial optimization problems and is of great importance for every University. In this paper, a hybrid evolutionary algorithm running on a GPU is employed to solve the examination timetabling problem. The hybrid evolutionary algorithm proposed has a genetic algorithm component and a greedy steepest descent component. The GPU computational capabilities allow the use of very large population sizes, leading to a more thorough exploration of the problem solution space. The GPU implementation, depending on the size of the problem, is up to twenty six times faster than the identical single-threaded CPU implementation of the algorithm. The algorithm is evaluated with the well known Toronto datasets and compares well with the best results found in the bibliography. Moreover, the selection of the encoding of the chromosomes and the tournament selection size as the population grows are examined and optimized. The compressed sparse row format is used for the conflict matrix and was proven essential to the process, since most of the datasets have a small conflict density, which translates into an extremely sparse matrix.

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