From: Li Zefan <lizf@cn.fujitsu.com>
To: Chester <somethingsome2000@gmail.com>
Cc: linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: defrag makes fragmentation worse
Date: Wed, 12 Oct 2011 10:37:41 +0800 [thread overview]
Message-ID: <4E94FD75.6040307@cn.fujitsu.com> (raw)
In-Reply-To: <CAAE6i0j=7ZoYnXsmNdWewmszSpaq4HLcy+M7--3s2hiy2p4TBA@mail.gmail.com>
05:15, Chester wrote:
> Okay, this pretty much confirms that autodefrag makes defrag totally
> useless.. The above email was with autodefrag turned off..
>
> With autodefrag on:
> 339 MB file
> initially 4 extents
>
> btrfs fi defrag filename
> filefrag filename
>
> about 900 extents
>
> I did btrfs defrag two more times and ended up with 2048 extents
>
> I attached the output of filefrag -v, which shows a pretty peculiar pattern.
This confirmed my speculation. I've fixed this bug a month ago, but
the patch hasn't hitted mainline.
You can try it out:
http://marc.info/?l=linux-btrfs&m=131495014823121&w=2
With this bug fixed, I think autodefrag won't be problematic.
--
Li Zefan
next prev parent reply other threads:[~2011-10-12 2:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-08 22:17 defrag makes fragmentation worse Chester
2011-10-11 6:19 ` Li Zefan
2011-10-11 20:47 ` Chester
[not found] ` <CAAE6i0j=7ZoYnXsmNdWewmszSpaq4HLcy+M7--3s2hiy2p4TBA@mail.gmail.com>
2011-10-12 2:37 ` Li Zefan [this message]
2011-10-12 4:14 ` Chester
2011-10-12 15:14 ` Chris Mason
-- strict thread matches above, loose matches on Subject: below --
2011-06-09 22:48 Johannes Hirte
2011-06-09 23:53 ` David Sterba
2011-06-23 0:12 ` Johannes Hirte
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