1. In sequential architectures programs tend to access data that has been accessed recently (temporal locality) or that is at an address near recently referenced data (spatial locality). This is the basis for the speed-up obtained with a cache memory.

2. In a multi-processor architecture with distributed memory it takes longer to access the memory attached to a different processor. This overhead increases with the number of communicating processors. Thus to efficiently employ many processors on a problem we must increase the proportion of references which are to local memory.

(01 Feb 1995)

Origin: L. Localitas: cf. F. Localite.

1. The state, or condition, of belonging to a definite place, or of being contained within definite limits. "It is thought that the soul and angels are devoid of quantity and dimension, and that they have nothing to do with grosser locality." (Glanvill)

2. Position; situation; a place; a spot; especially, a geographical place or situation, as of a mineral or plant.

3. Limitation to a county, district, or place; as, locality of trial.

4. <psychology> The perceptive faculty concerned with the ability to remember the relative positions of places.

(01 Mar 1998)