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Date: Sun, 25 Nov 2001 22:22:14 +1300
From: Chris Wedgwood <cw@f00f.org>
To: Andrew Morton <akpm@zip.com.au>
Cc: Steve Bergman <steve@rueb.com>, linux-kernel@vger.kernel.org
Subject: Re: Disk hardware caching, performance, and journalling
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On Sat, Nov 24, 2001 at 11:08:17AM -0800, Andrew Morton wrote:

    In theory, yes.  In my opinion, no.  For ext3, at least.  Caching
    isn't bad per-se.  It's reordering which can break the journalling
    constraints.

Some disks[1] most definately do reorder;  I've actually been able to
demonstrate this in some circumstances (it wasn't trivial to
produce and required several attempts).



  --cw

[1] SCSI, which we know does and will reorder writes when a barrier
    isn't specificed, it appears IDE drives can do the same but lack of
    hot-swap makes testing tedious :)
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