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From: Stan Hoeppner <stan@hardwarefreak.com>
To: xfs@oss.sgi.com
Subject: Re: NOW: o_direct   --  WAS: Re: WARNING in xfs_lwr.c, xfs_write()
Date: Thu, 27 May 2010 19:25:56 -0500	[thread overview]
Message-ID: <4BFF0D94.5030903@hardwarefreak.com> (raw)
In-Reply-To: <20100527114736.GA13112@infradead.org>

Christoph Hellwig put forth on 5/27/2010 6:47 AM:
> O_DIRECT is not a Posix standard and not very portable.  It originated
> on IRIX, and Linux inherited it during the 2.4 kernel series days.
> These days FreeBSD/NetBSD and AIX support it as well, but for example
> Solaris, HP-UX and OpenBSD don't, nevermind Windows or Mac OS.
> 
> I have no idea why the MTAs don't want to use it - it's generally easier
> to use then memory mapped I/O, and has much more deterministic
> performance.

Thanks for the background Christoph.  I can now see why Postfix and Dovecot in
particular don't use O_DIRECT: portability.  They both are developed to run on
every Unix/like OS you mention above, half of which don't offer O_DIRECT.  I'm
guessing the same may likely be true for the other SMTP MTAs and IMAP servers.

-- 
Stan

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  parent reply	other threads:[~2010-05-28  0:22 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-23  5:20 WARNING in xfs_lwr.c, xfs_write() Roman Kononov
2010-05-23  5:20 ` Roman Kononov
2010-05-23 10:18 ` Dave Chinner
2010-05-23 10:18   ` Dave Chinner
2010-05-23 14:23   ` Roman Kononov
2010-05-23 14:23     ` Roman Kononov
2010-05-24  1:19     ` Dave Chinner
2010-05-24  1:19       ` Dave Chinner
2010-06-12  5:00       ` Ilia Mirkin
2010-06-12  5:00         ` Ilia Mirkin
2010-06-13 22:47         ` Dave Chinner
2010-06-13 22:47           ` Dave Chinner
2010-06-13 23:10           ` Ilia Mirkin
2010-06-13 23:10             ` Ilia Mirkin
2010-06-14  1:29             ` Dave Chinner
2010-06-14  1:29               ` Dave Chinner
2010-06-14  3:27               ` Ilia Mirkin
2010-06-14  3:27                 ` Ilia Mirkin
2010-06-14 15:11                 ` Roman Kononov
2010-06-14 15:11                   ` Roman Kononov
2010-05-24  4:12     ` Stan Hoeppner
2010-05-24  5:16       ` Stewart Smith
2010-05-24 19:34       ` Roman Kononov
2010-05-26  7:06         ` Dave Chinner
2010-05-26 15:07           ` NOW: o_direct -- WAS: " Stan Hoeppner
2010-05-27 11:05             ` Michael Monnerie
2010-05-27 11:47             ` Christoph Hellwig
2010-05-27 13:58               ` Stewart Smith
2010-05-27 14:57                 ` Christoph Hellwig
2010-05-27 15:45                   ` Stewart Smith
2010-05-28  0:25               ` Stan Hoeppner [this message]
2010-05-27 14:05             ` Stewart Smith
2010-05-28  0:42               ` Stan Hoeppner

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