localityadditional

Localityadditional is a term used in computer science to describe a design principle that augments data structures with additional, locality-preserving information to improve cache locality and data access performance. The term combines locality of reference with an additive approach that places small, frequently used data alongside larger objects.

Origin and scope: The concept is discussed in memory hierarchy optimization, high-performance computing, and database systems, where accessing distant fields can trigger cache misses. Localityadditional proposes embedding or colocating auxiliary fields, indices, or small caches within an object or in adjacent memory regions to facilitate faster, more predictable access patterns.

Mechanisms and examples: Techniques include adding per-object meta-data fields that store computed neighbors or recently used flags, padding or aligning structures to match cache lines, using layout choices that maximize spatial locality, precomputed indices stored with data, or small local caches that reduce repeated dereferences. It can also refer to layout-aware algorithms that reorganize data to keep related items close together.

Advantages and criticisms: Proponents cite lower cache miss rates, higher bandwidth efficiency, and simpler control flow. Critics note increased memory usage, potential cache coherence overhead, and maintenance burden when data layouts change. The approach requires careful profiling to ensure benefits persist across workloads and architectures.

See also: locality of reference, data locality, cache-conscious programming, memory layout, SoA vs AoS.