From: Dave Chinner <david@fromorbit.com>
To: Mark Lord <kernel@teksavvy.com>
Cc: Christoph Hellwig <hch@infradead.org>,
xfs@oss.sgi.com, Linux Kernel <linux-kernel@vger.kernel.org>,
Stan Hoeppner <stan@hardwarefreak.com>,
Alex Elder <aelder@sgi.com>
Subject: Re: xfs: very slow after mount, very slow at umount
Date: Fri, 28 Jan 2011 10:41:52 +1100 [thread overview]
Message-ID: <20110127234152.GN21311@dastard> (raw)
In-Reply-To: <4D418B57.1000501@teksavvy.com>
On Thu, Jan 27, 2011 at 10:12:23AM -0500, Mark Lord wrote:
> On 11-01-27 12:30 AM, Stan Hoeppner wrote:
> > Mark Lord put forth on 1/26/2011 9:49 PM:
> >
> >> agcount=7453
> >
> > That's probably a bit high Mark, and very possibly the cause of your problems.
> > :) Unless the disk array backing this filesystem has something like 400-800
> > striped disk drives. You said it's a single 2TB drive right?
> >
> > The default agcount for a single drive filesystem is 4 allocation groups. For
> > mdraid (of any number of disks/configuration) it's 16 allocation groups.
> >
> > Why/how did you end up with 7452 allocation groups? That can definitely cause
> > some performance issues due to massively excessive head seeking, and possibly
> > all manner of weirdness.
>
> This is great info, exactly the kind of feedback I was hoping for!
>
> The filesystem is about a year old now, and I probably used agsize=nnnnn
> when creating it or something.
>
> So if this resulted in what you consider to be many MANY too MANY ags,
> then I can imagine the first new file write wanting to go out and read
> in all of the ag data to determine the "best fit" or something.
> Which might explain some of the delay.
>
> Once I get the new 2TB drive, I'll re-run mkfs.xfs and then copy everything
> over onto a fresh xfs filesystem.
>
> Can you recommend a good set of mkfs.xfs parameters to suit the characteristics
> of this system?
http://xfs.org/index.php/XFS_FAQ#Q:_I_want_to_tune_my_XFS_filesystems_for_.3Csomething.3E
And perhaps you want to consider the allocsize mount option, though
that shouldn't be necessary for 2.6.38+...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2011-01-27 23:39 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4D40C8D1.8090202@teksavvy.com>
2011-01-27 3:30 ` xfs: very slow after mount, very slow at umount Dave Chinner
2011-01-27 3:49 ` Mark Lord
2011-01-27 5:17 ` Stan Hoeppner
2011-01-27 15:12 ` Mark Lord
2011-01-27 15:40 ` Justin Piszcz
2011-01-27 16:03 ` Mark Lord
2011-01-27 19:40 ` Stan Hoeppner
2011-01-27 20:11 ` david
2011-01-27 23:53 ` Stan Hoeppner
2011-01-28 2:09 ` david
2011-01-28 13:56 ` Dave Chinner
2011-01-28 19:26 ` david
2011-01-29 5:40 ` Dave Chinner
2011-01-29 6:08 ` david
2011-01-29 7:35 ` Dave Chinner
2011-01-31 19:17 ` Christoph Hellwig
2011-01-27 21:56 ` Mark Lord
2011-01-28 0:17 ` Dave Chinner
2011-01-28 1:22 ` Mark Lord
2011-01-28 1:36 ` Mark Lord
2011-01-28 4:14 ` David Rees
2011-01-28 14:22 ` Mark Lord
2011-01-28 7:31 ` Dave Chinner
2011-01-28 14:33 ` Mark Lord
2011-01-28 23:58 ` Dave Chinner
2011-01-28 19:18 ` Martin Steigerwald
2011-01-27 20:24 ` John Stoffel
2011-01-27 23:41 ` Dave Chinner [this message]
2011-01-28 0:59 ` Mark Lord
2011-01-27 23:39 ` Dave Chinner
[not found] ` <4D40CDCF.4010301@teksavvy.com>
2011-01-27 3:43 ` Dave Chinner
2011-01-27 3:53 ` Mark Lord
2011-01-27 4:54 ` Mark Lord
2011-01-27 23:34 ` Dave Chinner
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