From: Werner Almesberger <wa@almesberger.net>
To: Bryan Henderson <hbryan@us.ibm.com>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: barriers vs. reads - O_DIRECT
Date: Thu, 24 Jun 2004 23:42:55 -0300 [thread overview]
Message-ID: <20040624234255.X1325@almesberger.net> (raw)
In-Reply-To: <OFC3DA214F.0857214B-ON88256EBD.00831E2D-88256EBE.0000EF26@us.ibm.com>; from hbryan@us.ibm.com on Thu, Jun 24, 2004 at 05:11:20PM -0700
Bryan Henderson wrote:
> There's also (kernel) aio to consider.
I suppose this would be the main scenario. AIO+O_DIRECT also
gives the closest approximation to directly talking to the
elevator.
> But I can't see how barriers figure into ordinary O_DIRECT file I/O.
Hmm, I've never looked at non-AIO write semantics with O_DIRECT.
For reasonable semantics, I guess it would either have to block
until the operation has completed, or be "atomic" (*).
(*) Defining atomic can be tricky, too. E.g. see
http://www.uwsg.iu.edu/hypermail/linux/kernel/0402.0/1361.html
- Werner
--
_________________________________________________________________________
/ Werner Almesberger, Buenos Aires, Argentina wa@almesberger.net /
/_http://www.almesberger.net/____________________________________________/
next prev parent reply other threads:[~2004-06-25 2:43 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-24 0:48 barriers vs. reads Werner Almesberger
2004-06-24 3:39 ` Werner Almesberger
2004-06-24 8:00 ` Herbert Poetzl
2004-06-24 12:16 ` Werner Almesberger
2004-06-24 13:36 ` Jamie Lokier
2004-06-24 17:02 ` Werner Almesberger
2004-06-24 16:39 ` Steve Lord
2004-06-24 17:00 ` barriers vs. reads - O_DIRECT Bryan Henderson
2004-06-24 17:46 ` Werner Almesberger
2004-06-24 18:50 ` Jamie Lokier
2004-06-24 20:55 ` Werner Almesberger
2004-06-24 22:42 ` Jamie Lokier
2004-06-25 3:21 ` Werner Almesberger
2004-06-25 3:57 ` Guy
2004-06-25 4:52 ` Werner Almesberger
2004-06-25 0:11 ` Bryan Henderson
2004-06-25 2:42 ` Werner Almesberger [this message]
2004-06-25 15:59 ` barriers vs. reads - O_DIRECT aio Bryan Henderson
2004-06-25 16:31 ` barriers vs. reads - O_DIRECT Bryan Henderson
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