Date: Sat, 30 Jun 2007 06:02:44 -0400
Message-ID: <87bqexiwu3.wl%peter@chubb.wattle.id.au>
From: peter@chubb.wattle.id.au
To: Christoph Hellwig <hch@infradead.org>, Jared Hulbert <jaredeh@gmail.com>,
       Nick Piggin <npiggin@suse.de>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Linux Memory Management List <linux-mm@kvack.org>,
       linux-fsdevel@vger.kernel.org
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Subject: Re: vm/fs meetup in september?
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>>>>> "Christoph" == Christoph Hellwig <hch@infradead.org> writes:

Christoph> On Tue, Jun 26, 2007 at 10:07:24AM -0700, Jared Hulbert
Christoph> wrote:
>> If you have a large array of a non-volatile semi-writeable memory
>> such as a highspeed NOR Flash or some of the similar emerging
>> technologies in a system.  It would be useful to use that memory as
>> an extension of RAM.  One of the ways you could do that is allow
>> pages to be swapped out to this memory.  Once there these pages
>> could be read directly, but would require a COW procedure on a
>> write access.  The reason why I think this may be a vm/fs topic is
>> that the hardware makes writing to this memory efficiently a
>> non-trivial operation that requires management just like a
>> filesystem.  Also it seems to me that there are probably overlaps
>> between this topic and the recent filemap_xip.c discussions.

Christoph> So what you mean is "swap on flash" ?  Defintively sounds
Christoph> like an interesting topic, although I'm not too sure it's
Christoph> all that filesystem-related.


You need either a block translation layer, or a (swap) filesystem that
understands flash peculiarities in order to make such a thing work.
The standard Linux swap format will not work.

--
Dr Peter Chubb  http://www.gelato.unsw.edu.au  peterc AT gelato.unsw.edu.au
http://www.ertos.nicta.com.au           ERTOS within National ICT Australia
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