From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Fri, 17 Dec 2004 14:11:59 -0800 (PST)
From: Christoph Lameter <christoph@lameter.com>
Subject: Re: [patch] CONFIG_ARCH_HAS_ATOMIC_UNSIGNED
In-Reply-To: <20041217193724.GA13542@wotan.suse.de>
Message-ID: <Pine.LNX.4.58.0412171410240.23925@server.graphe.net>
References: <E1Cf6EG-00015y-00@kernel.beaverton.ibm.com>
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 <20041217163308.GE14229@wotan.suse.de> <Pine.LNX.4.58.0412171118430.20902@server.graphe.net>
 <20041217193724.GA13542@wotan.suse.de>
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To: Andi Kleen <ak@suse.de>
Cc: Dave Hansen <haveblue@us.ibm.com>, linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>

On Fri, 17 Dec 2004, Andi Kleen wrote:

> On Fri, Dec 17, 2004 at 11:26:49AM -0800, Christoph Lameter wrote:
> > On Fri, 17 Dec 2004, Andi Kleen wrote:
> >
> > > > Put the order of the page there for compound pages instead of having that
> > > > in index?
> > >
> > > That would waste memory on the 64bit architectures that cannot tolerate
> > > 32bit atomic flags or on true 32bit architecture.
> >
> > Would be great to have 64 bit atomic support to fill this hole then.
>
> I think you lost me.   How would that help?

It would fill the hole on 64 bits if atomic_t would have the native word
size.

> To fill the hole you would need a 4 byte member with padding to move around,
> but there isn't one. You cannot also just add one because it would waste
> memory on 32bit archs and other 64bit archs.

There is no clean solution here but I just wanted to indicate what I would
like to see there if you want to use the space.

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