From: Alex Tomas <alex@clusterfs.com>
To: Eric Sandeen <sandeen@redhat.com>
Cc: Alex Tomas <alex@clusterfs.com>,
sho@tnes.nec.co.jp, tytso@mit.edu, jack@suse.cz,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org
Subject: Re: [RFC] Ext3 online defrag
Date: Fri, 27 Oct 2006 18:05:57 +0400 [thread overview]
Message-ID: <m364e5svju.fsf@bzzz.home.net> (raw)
In-Reply-To: <45420F76.90106@redhat.com> (Eric Sandeen's message of "Fri, 27 Oct 2006 08:53:58 -0500")
>>>>> Eric Sandeen (ES) writes:
ES> Alex Tomas wrote:
>> 3) scalable reservation
>> required for delayed allocation to avoid -ENOSPC at flush time.
>> current version uses per-sb spinlock.
ES> Can you elaborate on this issue? Shouldn't delayed allocation
ES> decrement free space immediately, and only the actual block location
ES> choice is delayed? Or is this due to potential extra metadata space
ES> required as blocks are allocated?
exactly. in this case, reservation has nothing to do with allocation
or preallocation of real blocks. this is just a *per-sb counter* of
blocks reserved for allocation at flush time. it includes all
non-allocated-yet blocks and metadata needed to allocate them (bitmaps,
group descriptors, blocks extent tree, etc). the previous version
of mballoc has reservation, but it doesn't scale very well being
a single global counter protected by the spinlock. at least, in many
regular loads I observed the reservation function in top30 of oprofile.
thanks, Alex
next prev parent reply other threads:[~2006-10-27 14:05 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-27 7:23 [RFC] Ext3 online defrag sho
2006-10-27 7:44 ` Alex Tomas
2006-10-27 13:53 ` Eric Sandeen
2006-10-27 14:05 ` Alex Tomas [this message]
2006-10-27 14:24 ` Eric Sandeen
2006-10-27 14:39 ` Alex Tomas
2006-11-15 9:54 ` Takashi Sato
[not found] <20061023122710.GA12034@atrey.karlin.mff.cuni.cz>
2006-10-23 14:16 ` Theodore Tso
2006-10-23 14:31 ` Alex Tomas
2006-10-23 14:48 ` Andreas Dilger
2006-10-23 14:55 ` Jan Kara
2006-10-23 14:51 ` Jan Kara
2006-10-23 15:01 ` Eric Sandeen
2006-10-24 4:14 ` Jeff Garzik
2006-10-24 13:59 ` David Chinner
2006-10-24 14:51 ` Dave Kleikamp
2006-10-24 16:01 ` David Chinner
2006-10-24 16:26 ` Dave Kleikamp
2006-10-25 1:18 ` David Chinner
2006-10-25 2:30 ` Barry Naujok
2006-10-25 2:42 ` Jeff Garzik
2006-10-25 4:27 ` David Chinner
2006-10-25 4:48 ` Jeff Garzik
2006-10-25 5:38 ` David Chinner
2006-10-25 6:01 ` Jeff Garzik
2006-10-25 8:11 ` David Chinner
2006-10-25 17:00 ` Jeff Garzik
2006-10-26 1:40 ` David Chinner
2006-10-26 3:33 ` Theodore Tso
2006-10-26 6:36 ` David Chinner
2006-10-26 13:37 ` Theodore Tso
2006-10-26 14:40 ` Dave Kleikamp
2006-10-26 11:37 ` Jan Kara
2006-10-27 1:32 ` David Chinner
2006-10-24 14:52 ` Eric Sandeen
2006-10-24 19:44 ` Theodore Tso
2006-10-24 20:31 ` Russell Cattelan
2006-10-24 23:00 ` Andreas Dilger
2006-10-25 14:54 ` Jan Kara
2006-10-25 17:02 ` Jeff Garzik
2006-10-25 17:58 ` Jan Kara
2006-10-25 18:08 ` Jeff Garzik
2006-10-25 18:25 ` Jan Kara
2006-10-25 18:33 ` Jeff Garzik
2006-10-26 9:30 ` Andreas Dilger
2006-10-25 2:09 ` David Chinner
2006-10-23 14:45 ` Jan Kara
2006-10-23 15:14 ` Andreas Dilger
2006-10-23 16:03 ` Jan Kara
2006-10-23 17:29 ` Andreas Dilger
2006-10-25 18:36 ` Jan Kara
2006-10-25 18:41 ` Jeff Garzik
2006-10-26 15:25 ` Jörn Engel
2006-10-24 4:13 ` Jeff Garzik
2006-10-24 4:21 ` Chris Wedgwood
2006-10-24 10:09 ` Jan Kara
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