I heard that page based I/O can improve performance, so some guys developed some page based I/O library which reads a file in page unit. For example, when we read the first byte, they will read an entire page (for example, 4k bytes) into memory, then when we are seeking to some other bytes inside a page, the bytes can be found from the page loaded in memory.
But, I also heard that when accessing OS File I/O, OS File I/O library implements page based I/O internally, for example, when you just read a byte using fseek or something, it will reads a whole page (maybe 4k or something) into memory.
My question is, which is true (OS provides page based I/O internally or not)? If OS provides page based I/O, why some guys always say that they are using page based I/O to improve performance.
thanks in advance,