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Re: WARNING in xfs_lwr.c, xfs_write()

To: xfs@xxxxxxxxxxx
Subject: Re: WARNING in xfs_lwr.c, xfs_write()
From: Roman Kononov <roman@xxxxxxxxxxxxxx>
Date: Mon, 24 May 2010 14:34:28 -0500
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References: <20100523002023.41f5a5c8@xxxxxxxxxxxxxxxxxxxxxxx> <20100523101856.GL2150@dastard> <20100523092344.0fcaab42@xxxxxxxxxxxxxxxxxxxxxxx> <4BF9FCA8.8090906@xxxxxxxxxxxxxxxxx>
On Sun, 23 May 2010 23:12:24 -0500 Stan Hoeppner
<stan@xxxxxxxxxxxxxxxxx> wrote:
> "The whole notion of "direct IO" is totally braindamaged. Just say no.
...
> From:  http://lkml.org/lkml/2007/1/10/235

I definitely measure dramatic overall performance benefit using
O_DIRECT carefully.

In that thread, it is doubtful that madvise+mmap+msync allow
asynchronous zero-copy reads and writes to/from already pinned by a
device driver memory of data produced/consumed by that device, without
cache pollution and with intelligent handling of disk errors. Am I
wrong?

Thanks,

Roman

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