On Fri, Jan 11, 2013 at 12:39:26PM +0530, Rajat Sharma wrote: > Default read/write inerfaces are better suited for sequential read/write > within your program. Although you can seek to any location within the file, > you still have overhead to issue system calls to get data. However mmap > allows you to map a section of file into program address space. Default read/write inerfaces does not move file's data to process address space ? when r/w a file descript which returnd by open() , how do the file data move from one place to another place ? For each time the write function being called , will kernel call filesystem's driver's write to respond ?? In my opinion,kernel will passed a buffer's head address which is passed form user-layer into driver,then driver will fill this buffer with file's data which is got by filesystem's read operation ? Am I right? Thanks! > > > -Rajat > > > On Fri, Jan 11, 2013 at 2:44 AM, horseriver <horserivers@xxxxxxxxx> wrote: > > > hi: > > > > these two wayes of operating one file : > > > > 1.use open/write interface call . > > > > 2.mmap this file into memory , then access this memory area and do r/w . > > > > what is the essential difference between this teo wayes? > > > > thanks! > > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
