Pretty much all Unixes these days have what is called a unified buffercache. If you don't know something about Unix history, this name is alittle puzzling, because what is it unifying?

The simple explanation is that originally Unix had the buffer cache,which cached blocks of recent disk IO (whether directly from userprocesses via read() and write() , or from internal kernel IO), andprocess virtual memory, used for the code and data of running processes.The buffer cache was statically

One of the rules of optimizing program performance is that there isno point in optimizing code that is not run very often; you optimizethe performance critical code, and then move on to other work. Thereis a similar principle in system design and system administration: improving an area that is not a concern to people does not reallyexcite them . To significantly improve people's lives, you have to workon something that they care about, something that is hurting them now.

An important consequence of people not caring