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Date: Wed, 7 Nov 2007 13:17:36 -0500
From: Rik van Riel <riel@redhat.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH 3/10] define page_file_cache
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On Wed, 7 Nov 2007 10:06:10 -0800 (PST)
Christoph Lameter <clameter@sgi.com> wrote:

> On Wed, 7 Nov 2007, Rik van Riel wrote:
> 
> > How exactly can an anonymous page ever become file backed?
> 
> When they get assigned a swap entry.

That does not change their status.  They're still swap backed.

> > > Do ramfs pages count as memory backed?
> > 
> > Since ramfs pages cannot be evicted from memory at all, they
> > should go into the "noreclaim" page set.
> 
> Which LRU do they go on.

With the patch set from last weekend, the file LRU.

With the patch set later this week, they'll be in the 
"noreclaim" page set, which is never scanned by the VM.

-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan