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Date: Thu, 5 Dec 2002 17:06:06 +1100
From: David Gibson <david@gibson.dropbear.id.au>
To: Miles Bader <miles@gnu.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>,
       "Adam J. Richter" <adam@yggdrasil.com>, linux-kernel@vger.kernel.org
Subject: Re: [RFC] generic device DMA implementation
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On Thu, Dec 05, 2002 at 12:17:55PM +0900, Miles Bader wrote:
> David Gibson <david@gibson.dropbear.id.au> writes:
> > It seems the "try to get consistent memory, but otherwise give me
> > inconsistent" is only useful on machines which:
> > 	(1) Are not fully consisent, BUT
> > 	(2) Can get consistent memory without disabling the cache, BUT
> > 	(3) Not very much of it, so you might run out.
> > 
> > The point is, there has to be an advantage to using consistent memory
> > if it is available AND the possibility of it not being available.
> ...
> > Are there actually any machines with the properties described above?
> 
> As I mentioned in my previous message, one of my platforms is like that
> memory, which is only 2 megabytes in size.

Ok, that starts to make sense then (what platform is it,
incidentally).  Is using consistent memory actually faster than doing
the cache flushes expliticly?  Much?

-- 
David Gibson			| For every complex problem there is a
david@gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.
http://www.ozlabs.org/people/dgibson
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