Date: Sat, 1 Mar 2008 12:21:56 -0500
From: Rik van Riel <riel@redhat.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-kernel@vger.kernel.org, Mel Gorman <mel@csn.ul.ie>,
       Nick Piggin <npiggin@suse.de>,
       Andrew Morton <akpm@linux-foundation.org>, apw@shadowen.org,
       linux-mm@kback.org
Subject: Re: [rfc 10/10] Pageflags land grab
Message-ID: <20080301122156.5994b949@bree.surriel.com>
In-Reply-To: <20080301040622.220638278@sgi.com>
References: <20080301040534.797979115@sgi.com>
	<20080301040622.220638278@sgi.com>
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On Fri, 29 Feb 2008 20:05:44 -0800
Christoph Lameter <clameter@sgi.com> wrote:

> We have enough page flags after vmemmap no longer uses section ids.
> 
> Reserve 5 of the 6 saved flags for functionality that is currently
> under development in the VM.
> 
> The new flags are only available if either of these conditions are met:
> 
> 1. 64 Bit system. (then we have 8 more free of the 32)
> 
> 2. !NUMA. In that case 2 bits are needed for the zone
>    id which leaves 30 page flag bits. Of those we use 24. 6 left.
> 
> 3. !SPARSEMEM. In that case we use 5 bits of the 30 available
>    for the node. 1 leftover.
> 
> 4. SPARSEMEM_VMEMMAP. Case 3 applies.

Nice!  I like your patch series.

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