Reference Work Entry

Encyclopedia of Parallel Computing

pp 1736-1741

Reordering

  • Michael HeathAffiliated withDepartment of Computer Science, University of Illinois at Urbana-Champaign

Definition

Reording for parallelism is a technique for enabling or enhancing concurrent processing of a list of items by determining an ordering that removes or reduces serial dependencies among the items.

Discussion

Ordered lists are ubiquitous and seem entirely natural in many aspects of daily life. But the specific order in which items are listed may be irrelevant, or even counterproductive, to the purpose of the list. In making a shopping list, for example, we usually list items in the order we happen to think of them, but rarely will such an order coincide with the most efficient path for locating the items in a store. Even for a structure that may have no natural linear ordering, such as a graph, we nevertheless typically number its nodes in some order, which may or may not facilitate efficient processing. In general, finding an optimal ordering is often a difficult combinatorial problem, as famously exemplified by the traveling salesperson problem.

Similarly, in ...

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