From: Andi Kleen <andi@firstfloor.org>
To: Ben Gamari <bgamari.foss@gmail.com>
Cc: Avi Kivity <avi@redhat.com>,
linux-btrfs@vger.kernel.org, Andi Kleen <andi@firstfloor.org>,
Arjan van de Ven <arjan@infradead.org>,
linux-kernel@vger.kernel.org, tytso@mit.edu, npiggin@suse.de,
mingo@elte.hu, Ruald Andreae <ruald.a@gmail.com>,
Jens Axboe <jens.axboe@oracle.com>, Olly Betts <olly@survex.com>,
martin f krafft <madduck@madduck.net>
Subject: Re: Poor interactive performance with I/O loads with fsync()ing
Date: Sun, 11 Apr 2010 19:20:07 +0200 [thread overview]
Message-ID: <20100411172007.GA11514@basil.fritz.box> (raw)
In-Reply-To: <4bc1fa59.c5c2f10a.776d.ffffcd91@mx.google.com>
> Has the reason for this been identified? Judging from the nature of metadata
> loads, it would seem that it should be substantially easier to implement
> fsync() efficiently.
By design a copy on write tree fs would need to flush a whole
tree hierarchy on a sync. btrfs avoids this by using a special
log for fsync, but that causes more overhead if you have that
log on the same disk. So IO subsystem will do more work.
It's a bit like JBD data journaling.
However it should not have the stalls inherent in ext3's journaling.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
prev parent reply other threads:[~2010-04-11 17:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4b9fa440.12135e0a.7fc8.ffffe745@mx.google.com>
[not found] ` <4baeaee5.c5c2f10a.7187.2688@mx.google.com>
[not found] ` <20100327204233.0d84542a@infradead.org>
[not found] ` <4baf624c.48c3f10a.16d0.ffffccb8@mx.google.com>
[not found] ` <87y6hcyu85.fsf@basil.nowhere.org>
[not found] ` <4bbf401e.a3b9e70a.13f3.4460@mx.google.com>
[not found] ` <4BC1E4A4.1070103@redhat.com>
2010-04-11 16:35 ` Poor interactive performance with I/O loads with fsync()ing Ben Gamari
2010-04-11 17:20 ` Andi Kleen [this message]
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