From mboxrd@z Thu Jan  1 00:00:00 1970
From: Krzysztof Adamski <k@adamski.org>
Subject: Re: very slow file deletion on an SSD
Date: Sun, 27 May 2012 09:15:04 -0400
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To: Stefan Ring <stefanrin@gmail.com>
Cc: Eric Sandeen <sandeen@sandeen.net>, Joe Landman <joe.landman@gmail.com>, linux-raid <linux-raid@vger.kernel.org>, xfs@oss.sgi.com
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On Sun, 2012-05-27 at 09:34 +0200, Stefan Ring wrote:
> >> [root@siFlash test]# xfs_bmap -vp 2.r.96.0
> >> xfs_bmap: xfsctl(XFS_IOC_GETBMAPX) iflags=0x4 ["2.r.96.0"]: Cannot allocate memory
> >
> > Try filefrag -v maybe, if your e2fsprogs is new enough.
> >
> > Trying to remember, ENOMEM in bmap rings a bell... but this is possibly indicative of an extremely fragmented file.
> 
> True, I've had it happen with extremely fragmented files.
> 
> I've started playing around with discard myself only recently, but so
> far I like the approach of using fstrim a lot better than the discard
> option: http://xfs.org/index.php/FITRIM/discard

Check what blockdev --getra <md device> is set to. I used to have a
several second deletes on large (4GB) fragmented files when ra was the
default 256. Once I changed it to 4096 (best value will depend on your
setup) the deletes became instant.

K