hacking - aio_sendfile()

[Konstantin Belousov]

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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