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Date: Tue, 22 Apr 2003 11:09:53 -0400 (EDT)
From: Ingo Molnar <mingo@redhat.com>
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To: "Martin J. Bligh" <mbligh@aracnet.com>
cc: Andrew Morton <akpm@digeo.com>, Andrea Arcangeli <andrea@suse.de>,
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       Linus Torvalds <torvalds@transmeta.com>, <linux-kernel@vger.kernel.org>,
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Subject: Re: objrmap and vmtruncate
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On Tue, 22 Apr 2003, Martin J. Bligh wrote:

> Oh, BTW. You're assuming no sharing of any pages in the above. Look what
> happens if 1000 processes share the same page ...

i'm not assuming anything - this is the per-process overhead.

processes have well-known RAM overhead associated to the size (and
fragmentation) of their virtual memory space, primarily caused by
pagetables. My suggestion triples this cost [where pte chains double the
costs], but leaves the scaling factor and generic characteristics the
same.

	Ingo