Re: [3/4] kevent: AIO, aio_sendfile() implementation.

From: Badari Pulavarty
Date: Thu Jul 27 2006 - 11:26:03 EST


Sébastien Dugué wrote:
On Wed, 2006-07-26 at 09:22 -0700, Badari Pulavarty wrote:
Ulrich Drepper wrote:
Christoph Hellwig wrote:
My personal opinion on existing AIO is that it is not the right design.
Benjamin LaHaise agree with me (if I understood him right),
I completely agree with that aswell.
I agree, too, but the current code is not the last of the line. Suparna
has a st of patches which make the current kernel aio code work much
better and especially make it really usable to implement POSIX AIO.

In Ottawa we were talking about submitting it and Suparna will. We just
thought about a little longer timeframe. I guess it could be
accelerated since he mostly has the patch done. But I don't know her
schedule.

Important here is, don't base any decision on the current aio
implementation.
Ulrich,

Suparna mentioned your interest in making POSIX glibc aio work with kernel-aio at OLS.
We thought taking a re-look at the (kernel side) work BULL did, would be a nice starting
point. I re-based those patches to 2.6.18-rc2 and sent it to Zach Brown for review before
sending them out to list.

These patches does NOT make AIO any cleaner. All they do is add functionality to support
POSIX AIO easier. These are

[ PATCH 1/3 ] Adding signal notification for event completion

[ PATCH 2/3 ] lio (listio) completion semantics

[ PATCH 3/3 ] cancel_fd support

Badari,

Thanks for refreshing those patches, they have been sitting here
for quite some time now and collected dust.

I also think Suparna's patchset for doing buffered AIO would be
a real plus here.

Suparna explained these in the following article:

http://lwn.net/Articles/148755/

If you think, this is a reasonable direction/approach for the kernel and you would take care
of glibc side of things - I can spend time on these patches, getting them to reasonable shape
and push for inclusion.

Ulrich, I you want to have a look at how those patches are put to
use in libposix-aio, have a look at http://sourceforge.net/projects/paiol.

It could be a starting point for glibc.

Thanks,

Sébastien.

Sebastien,

Suparna mentioned at Ulrich wants us to concentrate on kernel-side support, so that he
can look at glibc side of things (along with other work he is already doing). So, if we
can get an agreement on what kind of kernel support is needed - we can focus our
efforts on kernel side first and leave glibc enablement to capable hands of Uli :)

Thanks,
Badari

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