From: "Mike Snitzer" <snitzer@gmail.com>
Subject: Re: Online ext4 defragmention
Date: Mon, 12 Jan 2009 08:39:33 -0500
Message-ID: <170fa0d20901120539w4e3bbc03na39f01edde206d25@mail.gmail.com>
References: <20090111134443.581cfc83@lithium.local.net>
	 <20090111202838.GA29383@mit.edu>
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Cc: "Alex Buell" <alex.buell@munted.org.uk>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	linux-ext4@vger.kernel.org
To: "Theodore Tso" <tytso@mit.edu>
In-Reply-To: <20090111202838.GA29383@mit.edu>
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Sender: linux-ext4-owner@vger.kernel.org

On Sun, Jan 11, 2009 at 3:28 PM, Theodore Tso <tytso@mit.edu> wrote:
> On Sun, Jan 11, 2009 at 01:44:43PM +0000, Alex Buell wrote:
>> Can someone confirm if the online ext4 defragmentation ioctls will
>> be going into 2.6.29? Thanks, I'm planning a migration from a
>> disparate collection of filesystems to ext4 over the next few months.
>
> Unfortunately, the defragmentation patches need to a lot of work (to
> be honest, largely refactored and almost rewritten) before they are
> ready to for mainline yes.  I am also concerned that the current
> defrag patches also try too hard to keep blocks in the same block
> group, even as a higher priority keeping them non-fragmented.
>
> Also, note that some of the benefits of ext4 only show up if you do a
> backup, mkfs, and restore; that's because there are layout changes
> that can only take place if you reformat the filesystem.  Finally,
> there are some allocation algorithm changes which didn't make the
> 2.6.29 merge window which I think will make a long-term difference.
> So you'll probably want to use 2.6.29 with the ext4 patch set.

Hi Ted,

Could you elaborate on which allocation patches you're referring to in
the ext4 patch queue (2.6.28-ext4-3?) ?

Thanks,
Mike