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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4E94FD75.6040307@cn.fujitsu.com \
--to=lizf@cn.fujitsu.com \
--cc=linux-btrfs@vger.kernel.org \
--cc=somethingsome2000@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.