CACHETHRESHOLD

CACHETHRESHOLD is a configurable parameter used in caching systems to decide whether an item should be stored in a cache. It specifies the minimum expected benefit required for caching to be worthwhile, and its exact meaning can vary among implementations.

Typically, a cache estimates the potential benefit of caching an item in terms of reduced retrieval latency, lower bandwidth cost, or improved overall performance. If the estimated benefit exceeds the threshold, the item is added to the cache; otherwise it is not cached. This decision is often combined with the cache's existing eviction and replacement policies.

Applications vary by domain. In software in-memory caches, CACHETHRESHOLD might depend on access frequency, size, or predicted latency savings. In hardware caches, the threshold can influence whether a data block is brought into a faster cache level based on reuse distance or access cost. In content delivery networks, thresholds may determine whether to store content at an edge node based on expected demand and transfer cost.

Tuning: Choosing a suitable threshold involves trading memory usage against hit rate. A too-low threshold can cause cache pollution by storing items that will not be reused, while a too-high threshold may miss caching opportunities. Many systems use static thresholds that are adjusted during testing or employ adaptive schemes that adjust threshold based on workload measurements.

See also: caching, cache eviction policy, prefetching, cache pollution.