The Buffer Cache

Linux no longer has a distinct buffer cache. Way back in the 2.2 kernel, there were two separate disk caches: the page cache and the buffer cache. The former cached pages; the latter cached buffers. The two caches were not unified in the least; a disk block could exist in both caches simultaneously. This led to extensive effort in synchronization between the two cached copiesnot to mention wasted memory.

This was the case in the 2.2 Linux kernel and earlier, but starting with the 2.4 Linux kernel the two caches were unified. Today, we have one disk cache: the page cache.

The kernel still needs to use buffers, however, to represent disk blocks in memory. Thankfully, the buffers describe the mapping of a block onto a page, which is in the page cache.