linux-kernel - Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache control

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Message-Id: <1276535371.6437.7417.camel@nimitz>
Date:	Mon, 14 Jun 2010 10:09:31 -0700
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	balbir@...ux.vnet.ibm.com
Cc:	Avi Kivity <avi@...hat.com>, kvm <kvm@...r.kernel.org>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page
 cache control

On Mon, 2010-06-14 at 22:28 +0530, Balbir Singh wrote:
> If you've got duplicate pages and you know
> that they are duplicated and can be retrieved at a lower cost, why
> wouldn't we go after them first?

I agree with this in theory.  But, the guest lacks the information about
what is truly duplicated and what the costs are for itself and/or the
host to recreate it.  "Unmapped page cache" may be the best proxy that
we have at the moment for "easy to recreate", but I think it's still too
poor a match to make these patches useful.

-- Dave

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