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Cache (Categories of Cache (Cache comes in three categories; level 1, 2…
Cache
Categories of Cache
Cache comes in three categories; level 1, 2 and 3
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Level 2 Cache - Traditionally was external to the CPU on an external chip but most modern CPU's have this integrated on the edge of the CPU
Level 3 Cache - As most modern CPU's have level 2 cache integrated into their architecture, level 3 cache is the name given to the extra cache that is integrated into the motherboard between the CPU and main memory
Three Key Principles
Temporal Locality - Data is initially accessed by the CPU but the cache retains the data for future used as the CPU will need it again saving time
Spatial Locality - The CPU access data in a particular memory location, the cache knows that the CPU will also require related data stored close to the original and so fetches this as well, anticipating future demand
The size and organisation of the cache are important considerations, the cache is organised based on three key principles involved
Sequential Locality - The CPU calls data and knows that it is likely that it will need data in the sequences next location (S + 1) and so fetches that data as well
Buffers
A buffer is used as a temporary data store to refrain data from the processor via the cache whilst information is being written to a storage device
The processor is by far the fastest component in a computer however storage devices cannot operate at the same high speeds
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What is Cache?
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It helps to speed up the data transfer process, ensuring that the CPU is always supplied with the data it needs
Cache hit and miss
When the CPU requests a piece of data, and the CPU locates the data in the cache, it is called a cache hit
When the CPU requests a piece of data, and the CPU fails to discover the data requests in the cache, it is known as a cache miss
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Cache Size
The bigger the cache's capacity, the faster the CPU will be able to operate as it is more likely to score a cache hit