> David Schwartz пишет: > > You have a misunderstanding about the semantics of 'sendfile'. > The 'sendfile' function is just a more efficient version of a > read followed by a write. If you did a read followed by a write, > it would block as well (in the read). > > > > DS
> sendfile function is not just a more efficient version of a read > followed by a write. It reads from one fd and write to another at tha > same time. Please try to read 2G, and then write 2G - and how much > memory you will be need and how much time you will loose while reading > 2G from disk, but not writing them to socket. You are correct. What I meant to say was that it's just a more efficient version of 'mmap'ing a file and then 'write'ing from the 'mmap'. The 'write' to a non-blocking socket can still 'block' on disk I/O. > If you know more > efficient method to transfer file from disk to network - please advise. > Now all I want is really non-blocking sendfile. Currently sendfile is > non-blocking on network, but not on disk i/o. And when I have network > faster than disk - I get block. There are many different techniques and which is correct depends on what direction you want to go. POSIX asynchronous I/O is one possibility. Threads plus epoll is another. It really depends upon how much performance you need, how much complexity you can tolerate, and how portable you need to be. DS - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
