linux-kernel - Re: [PATCH 0/4] (RESEND) ext3[34] barrier changes

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Date:	Mon, 19 May 2008 09:26:41 -0400
From:	Chris Mason <chris.mason@...cle.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Eric Sandeen <sandeen@...hat.com>, linux-ext4@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	jamie@...reable.org
Subject: Re: [PATCH 0/4] (RESEND) ext3[34] barrier changes

On Sunday 18 May 2008, Andi Kleen wrote:
> Andrew Morton <akpm@...ux-foundation.org> writes:
> > On Fri, 16 May 2008 14:02:46 -0500
> >
> > Eric Sandeen <sandeen@...hat.com> wrote:
> >> A collection of patches to make ext3 & 4 use barriers by
> >> default, and to call blkdev_issue_flush on fsync if they
> >> are enabled.
> >
> > Last time this came up lots of workloads slowed down by 30% so I
> > dropped the patches in horror.
>
> Didn't ext4 have some new checksum trick to avoid them?

I didn't think checksumming avoided barriers completely.  Just the barrier 
before the commit block, not the barrier after.

-chris
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