What is cache memory and what is it for?

The cache memory is one of the most important specifications of the processor and it is a data that is always provided by the manufacturers. Surely you have ever wondered what cache memory is and what it is for, to try to solve these doubts we have prepared this article in which we try to explain it in a very simple and understandable way. The objective of this article is not to delve into the related concepts in this memory system but to explain it in a clear and understandable way.

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Cache memory: concept and operation

Before seeing what cache memory is, we need to be clear about how a processor works in our computers, in a very simple way we can summarize it by saying that it takes the data it needs to work from RAM memory. When the processor needs to access information to do its tasks, this information is requested from the RAM, which provides it to the processor as fast as it can. This process is not instantaneous, but it takes a while, it is only a few nanoseconds, but, although it seems to us that it is nothing, it is actually a world and while the processor is waiting, the opportunity to do other calculations and operations is lost.

To solve this problem the cache memory was created, this is nothing more than a small amount of memory that is inside the processor, the purpose of the cache memory is to make access to information by the processor as fast as possible. The cache memory is inside the processor so the information has to travel very little to reach the place where it is processed, so the time it takes to access it is much shorter than in the case of RAM.

The amount of this memory is minuscule compared to RAM, a current high-end PC may have 32GB or more of RAM but the maximum amount of cache is between 6MB and 20MB generally. This is also important since the time it takes to access a data in memory is proportional to the amount of it. Therefore, we have that access to the cache is much faster than access to RAM and it is also closer and the data has to travel less distance.

The processor cache is organized in several levels, most of the current processors have three levels of this memory, it is what is known as L1, L2 and L3 cache. The L1 cache is inside the processor cores and is the fastest, on the contrary, its quantity is very limited since it is usually 32 KB maximum. The smallest and most frequently needed data is stored in this cache.

Next, we have the L2 cache that is outside the cores, but very close to these, the amount of this memory is usually about 256 KB and is second in speed. Finally, we have the L3 cache that is the furthest from the cores and the slowest, its advantage is that the amount is much greater and can reach 4-20 MB or even more in the case of professional processors with many cores.

Summary and final conclusion

As a summary and conclusion we can say that the processor cache memory is the solution to the memory system performance problem, it is in charge of accelerating the readings and writes that the processor needs to do on the main memory system to achieve a higher overall performance of the system. It is a memory that is inside the processor itself in very small quantities, but it is extremely important for it to function properly.