how to resolve user-buffered I/O

[sysabod]

hi all:
i read a book which said that the class of i/o methods accompanied with c standard library is called user-buffered I/O excluding methods like read and write provided by linux system .

so,what is "buffering done in user space"? Which one is more efficient,read and its counterpart fread,etc ?

thanks in advance!

[PanGalactic]

These days, operating systems do a much better job of buffering I/O. Buffering involved copying data in memory, and the less you can do of that the better. Besides, the buffer sizes used in most libraries are way to small to make any difference on modern systems. In order of efficiency: mmap, read, fread.