From owner-freebsd-net@FreeBSD.ORG  Wed Oct 20 20:27:54 2004
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Date: Thu, 21 Oct 2004 00:27:52 +0400 (MSD)
From: Igor Sysoev <is@rambler-co.ru>
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To: "Christopher M. Sedore" <cmsedore@maxwell.syr.edu>
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cc: freebsd-net@freebsd.org
cc: "Ronald F. Guilmette" <rfg@monkeys.com>
Subject: RE: aio_connect ?
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On Wed, 20 Oct 2004, Christopher M. Sedore wrote:

> > While the developing my server nginx, I found the POSIX aio_*
> > operations
> > uncomfortable. I do not mean a different programming style, I mean
> > the aio_read() and aio_write() drawbacks - they have no scatter-gather
> > capabilities (aio_readv/aio_writev) and they require too many
> > syscalls.
> > E.g, the reading requires
> > *) 3 syscalls for ready data: aio_read(), aio_error(), aio_return()
> > *) 5 syscalls for non-ready data: aio_read(), aio_error(),
> >    waiting for notification, then aio_error(), aio_return(),
> >    or if timeout occuired - aio_cancel(), aio_error().
>
> This is why I added aio_waitcomplete().  It reduces both cases to two
> syscalls.

As I understand aio_waitcomplete() returns aiocb of any complete AIO
operation but I need to know the state of the exact AIO, namely the last
aio_read().

I use kqueue to get AIO notifications. If AIO operation would fail
at the start, will kqueue return notificaiton about this operation ?


Igor Sysoev
http://sysoev.ru/en/