From: Dave Chinner <david@fromorbit.com>
To: Andrei Deftu <andreideftu@gmail.com>
Cc: xfs@oss.sgi.com
Subject: Re: Slow delete
Date: Tue, 6 Jul 2010 09:34:48 +1000 [thread overview]
Message-ID: <20100705233448.GB24712@dastard> (raw)
In-Reply-To: <AANLkTinPmhJRD3CDdsHtkLFzYd2jF9ee7gPqgO6XBSfl@mail.gmail.com>
On Mon, Jul 05, 2010 at 05:27:44PM +0300, Andrei Deftu wrote:
> Hi,
>
> As many people have pointed out, xfs is very slow when deleting a
> large number of files. Does anyone has a technical answer to this
> problem? Also, I am interested to know if there is a way to
> temporarily speed up the delete process, regardless of all the other
> parameters.
The technical reason is to do with the architecture of the
transaction and logging subsystem of XFS. The key concept: relogging
of dirty objects. The reason it affects unlinks: removing files
from the same directory modifies the same objects repeatedly (e.g.
the directory btree blocks).
For a detailed explanation of the concept and how delayed logging
takes advantage of it to speed up stuff like deleting a large number
of files, see:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=Documentation/filesystems/xfs-delayed-logging-design.txt
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2010-07-05 23:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <AANLkTinPmhJRD3CDdsHtkLFzYd2jF9ee7gPqgO6XBSfl@mail.gmail.com>
2010-07-05 15:13 ` Slow delete Emmanuel Florac
2010-07-05 15:33 ` Andrei Deftu
2010-07-05 18:21 ` Peter Grandi
2010-07-05 18:54 ` Christoph Hellwig
2010-07-05 23:34 ` Dave Chinner [this message]
2010-07-12 12:17 ` Michael Monnerie
2010-07-19 18:54 ` Alex Elder
2010-07-20 11:04 ` Michael Monnerie
2010-07-20 17:09 ` Stan Hoeppner
2010-07-20 23:18 ` Dave Chinner
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