From: Christoph Hellwig <hch@infradead.org>
To: Florian Weimer <fweimer@bfk.de>
Cc: xfs@oss.sgi.com
Subject: Re: XFS on 2.6.26: reading the first 4K of a large file takes ages
Date: Wed, 19 May 2010 07:48:26 -0400 [thread overview]
Message-ID: <20100519114826.GA18224@infradead.org> (raw)
In-Reply-To: <8239xojfco.fsf@mid.bfk.de>
On Wed, May 19, 2010 at 11:33:27AM +0000, Florian Weimer wrote:
> We've got a couple of rather large files, and with a cold cache,
> reading the first 4K bytes of the file (e.g., just running
> "head --bytes 4096" on it) takes ages, up to several minutes,
> sometimes triggering the hang check timer.
>
> I wonder if XFS reads the whole extent information into RAM when the
> file is opened. Is this the case, at least on 2.6.26? Has this
> changed in later versions, perhaps?
Yes, XFS always reads in the extent map, and no this hasn't changed
recently.
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next prev parent reply other threads:[~2010-05-19 11:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-19 11:33 XFS on 2.6.26: reading the first 4K of a large file takes ages Florian Weimer
2010-05-19 11:48 ` Christoph Hellwig [this message]
2010-05-19 23:27 ` Dave Chinner
2010-05-20 12:11 ` Florian Weimer
2010-05-21 6:20 ` Stewart Smith
2010-05-21 6:43 ` Florian Weimer
2010-05-21 8:26 ` Dave Chinner
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