From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christian Borntraeger <borntraeger@de.ibm.com>
Subject: Re: [patch] rewrite rd
Date: Tue, 4 Dec 2007 10:54:51 +0100
Message-ID: <200712041054.51599.borntraeger@de.ibm.com>
References: <20071204042628.GA26636@wotan.suse.de>
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Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Andrew Morton <akpm@linux-foundation.org>, rob@landley.net,
	Jens Axboe <axboe@kernel.dk>
To: Nick Piggin <npiggin@suse.de>
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Am Dienstag, 4. Dezember 2007 schrieb Nick Piggin:
[...]
> There is one slight downside -- direct block device access and filesystem
> metadata access goes through an extra copy and gets stored in RAM twice.
> However, this downside is only slight, because the real buffercache of the
> device is now reclaimable (because we're not playing crazy games with it),
> so under memory intensive situations, footprint should effectively be the
> same -- maybe even a slight advantage to the new driver because it can also
> reclaim buffer heads.

This is just an idea, I dont know if it is worth the trouble, but have you
though about implementing direct_access for brd? That would allow 
execute-in-place (xip) on brd eliminating the extra copy.

Christian