What Is a Write Buffer?

In computer architecture, there are pieces of memory known as buffers. These buffers are small and hold information that must be able to be quickly accessed. A write buffer, which is held in the central processing unit (CPU) cache, holds information that must be capable of being written from the buffer to the random access memory (RAM) area of the computer. Most data from the cache are read and not written, so the write buffer is tiny compared to the read section of the cache. The write buffer can only handle one write request at a time, so only one piece of datum is released when a write request is received.

In memory architecture, regardless of whether the memory is from the CPU or RAM, there is a section called a cache. This represents a very small piece of the whole memory, and it stores previously read data so they can be recovered later. By storing the information, the computer will be able to recall it much quicker and easier when the user accesses it again.

A write buffer, which is exclusively stored in the CPU cache, stores information for writing. The difference between a read and write request is how the information is handled. In a read request, the information is recovered as is, without any changes or computations. A write request is more complicated, because the information has to be changed or computed before it can be used.

The majority of requests are read requests, such as recalling a static website or opening a previously saved document that has not changed. The write buffer helps to organize the entire buffer. Instead of having all the read and write requests in one place, which can dramatically reduce cache speed, the write information is only stored in one section so this section can work exclusively on write requests. The rest of the cache is then left to work on the predominant read requests.

In the write buffer, requests can only be handled one at a time. Instead of the read section of the cache, which handles many requests at once, the write section can only release information for one request. This is primarily because write requests are more difficult to fill, so the cache has to concentrate on the one task.

While the buffer can only fill one write request at a time, it still moves quickly. Write requests only need a small chunk of information to work, and the data are recalled within milliseconds. Even though they are slower than read requests, the write requests are still filled with just a short-time delay.