On Tue, 25 Mar 2008 18:10:14 +0530 "Vijay Chauhan" <kernel.vijay@xxxxxxxxx> wrote: > what is asynchronous read/write operation? How it is different from > normal read/write operation? > Normally i have seen that the file read/write operation is set to > do_sync_read/write which in turns call to aio_read/write. So I could > not able understand the difference. After you do a normal read, the data you wanted is in the buffer you specified. This magic happens because the read syscall code will wait for the data to be present, before returning to userspace. If you do an AIO read operation, the syscall will return immediately, even if the data has not been read from disk yet. Your program cannot use the buffer yet. Only after the IO has finished, and the kernel has sent an AIO completion event, can you use the data. In short, AIO is more difficult to use, but you can have multiple such IOs happening at the same time because your program can do other things (like issuing more AIO requests) while IO happens. Things are similar on the write side. -- All rights reversed. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
