Prefetching is a technique used in computing to improve performance by retrieving data or instructions before they are needed. By predicting what a program will request in the future, the system can load information in advance to reduced wait times .

Prefetching is used in various areas of computing, including CPU architectures and operating systems. It can be implemented in both hardware and software, and it relies on detecting access patterns that suggest what data is likely to be needed soon.

Prefetching works by predicting which memory addresses or resources will be accessing and load them into faster access storage, like caches.

Prefetching may be used:

Processors (CPU's) often include prefetching that attempts to reduce cache misses by loading data into cache before it is requested by the running program. This is for programs that access memory in predictable patterns, such as loops that iterate over arrays.

Hardware prefetching is can be done without software involvement and can be found in most modern CPU's. For example, Intel CPU's feature a variety of prefetch that work across multiple cache levels.

Prefetch instructions can be written into the code by the programmer or by the compiler. Prefetch instructions specify the memory addresses to be prefetched and the desired prefetch distance.

In software, there are instructions that can be written with: