On Thu, Jul 11, 2013 at 02:39:00AM -0700, Adrian Chadd wrote: > On 11 July 2013 02:36, Konstantin Belousov <kostikbel_at_gmail.com> wrote: > > > No, it is not disk I/O which is problematic there. It is socket I/O > > e.g. wait for the socket buffers lomark in the kern_sendfile() which > > causes unbounded sleep. Look for the sbwait() call, both in the > > kern_sendfile() itself, and in the pru_send methods of the protocols, > > e.g. in sosend_generic(). The wait scope controlled by the other side of > > connection and allow it to completely block the aio subsystem. > > > > Disk I/O is supposed to finish in the finite time. > > Even if the destination socket is marked as NONBLOCK? You mean, would a sleep for the socket buffer space cause aio thread block is the socket is put in nonblocking mode ? Or something else ? No, it would not block the thread. But I cannot consider the aio_sendfile(2) implementation useful if it requires non-blocking socket. Also, what about other thread changing the socket to blocking mode while sendfile is in flight ?
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