Date: Fri, 4 Dec 2009 19:53:03 +0100
From: Andrea Arcangeli <aarcange@redhat.com>
To: Chris Wright <chrisw@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Rik van Riel <riel@redhat.com>,
       Hugh Dickins <hugh.dickins@tiscali.co.uk>,
       Andrew Morton <akpm@linux-foundation.org>,
       Izik Eidus <ieidus@redhat.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org
Subject: Re: [PATCH 2/9] ksm: let shared pages be swappable
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On Fri, Dec 04, 2009 at 09:16:40AM -0800, Chris Wright wrote:
> That's why I mentioned the page of zeroes as the prime example of
> something with a high mapcount that shouldn't really ever be evicted.

Just a nitpick, "never" is too much, it should remain evictable if
somebody halts all VM from monitor and starts a workloads that fills
RAM and runs for a very prolonged time pushing all VM into swap. This
is especially true if we stick to the below approach and it isn't
just 1 page in high-sharing.

> It's a somewhat special case, but wouldn't it be useful to have a generic
> method to recognize this kind of sharing since it's a generic issue?

Agreed.
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