#What is the fastest memory that CPU can access?
The memory with the fastest CPU access speed is Cache. Cache is a kind of memory used in the CPU to temporarily save the calculation results of the CPU. Its access speed is much faster than the memory but slower than the CPU. Adding the cache to the CPU can reduce the delay of the CPU accessing the stored data, thereby improving the performance of the computer. .
Introduction to CPU Cache:
In computer systems, the CPU cache (English: CPU Cache, referred to as cache in this article) is a component used to reduce the average time required for the processor to access memory . In the pyramid storage system, it is located at the second level from top to bottom, second only to the CPU registers. Its capacity is much smaller than memory, but its speed can be close to the frequency of the processor.
When the processor issues a memory access request, it will first check whether there is requested data in the cache. If it exists (hit), the data is returned directly without accessing the memory; if it does not exist (invalid), the corresponding data in the memory must be loaded into the cache first, and then returned to the processor.
The reason why caching is effective is mainly because the access to memory when the program is running presents locality characteristics. This locality includes both spatial locality (Spatial Locality) and temporal locality (Temporal Locality). Effectively exploiting this locality, caches can achieve extremely high hit rates.
From the perspective of the processor, the cache is a transparent component. Therefore, programmers usually cannot directly intervene in the operation of the cache. However, it is possible to make better use of the cache by implementing specific optimizations into your program code based on the characteristics of the cache.
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