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Subject: Re: [RFC] Arch option to touch newly allocated pages
To: jdike@karaya.com (Jeff Dike)
Date: Mon, 4 Mar 2002 22:49:58 +0000 (GMT)
Cc: alan@lxorguk.ukuu.org.uk (Alan Cox), linux-kernel@vger.kernel.org
In-Reply-To: <200203042046.PAA04125@ccure.karaya.com> from "Jeff Dike" at Mar 04, 2002 03:46:07 PM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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> OK, when something calls alloc_pages and gets back some pages, it's almost
> always going to modify them immediately, right?

Yes. Which is why we don't allocate the when you map an object or create
a shmem fs file

> If this is true, then what I'm proposing would force the host to find backing
> memory for those pages a tiny bit earlier than it would have had to otherwise.

In the normal case about half of the pages are never allocated that are
mapped. In other words no alloc_pages was ever done for them or will ever
be needed. 

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