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Date: Tue, 29 Nov 2005 17:47:00 +0100
From: Martijn van Oosterhout <kleptog@svana.org>
To: David Boreham <david_list@boreham.org>
Cc: pgsql-hackers@postgresql.org
Subject: Re: ice-broker scan thread
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Reply-To: Martijn van Oosterhout <kleptog@svana.org>
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On Tue, Nov 29, 2005 at 08:42:18AM -0700, David Boreham wrote:
>=20
> >Unfortunatly I can't really test it at it's full potential because it
> >uses glibc's default POSIX AIO which is *lame*. No more than one
> >outstanding request per fd which for PostgreSQL is crappy. There was
> >=20
> I had the impression from the kernel aio mailing list a while back
> that post-<some kernel version> linux, the POSIX aio calls were
> forwarded to the kernel aio interface. Or are you saying that the
> POSIX API itself imposes that limitation ?

By default when you use aio you get the version in libc (-lrt IIRC)
which has the issue I mentioned, probably because it's probably
optimised for the lots-of-network-connections type program where
multiple outstanding requests on a single fd are not meaningful. You
can however link in some other library which gives you kernel support.
However, I don't have a new enough kernel to have the kernel support so
I havn't tested that.

POSIX AIO doesn't prescribe either way.

Have a nice day,
--=20
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.

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