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From: Martin Bligh <mbligh@google.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"nickpiggin@yahoo.com.au" <nickpiggin@yahoo.com.au>,
	"Lee.Schermerhorn@hp.com" <Lee.Schermerhorn@hp.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC][PATCH] overwride page->mapping [0/3] intro
Date: Wed, 12 Sep 2007 12:12:25 -0700	[thread overview]
Message-ID: <46E83A19.2090604@google.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0709121207400.1934@schroedinger.engr.sgi.com>

Christoph Lameter wrote:
> On Wed, 12 Sep 2007, Balbir Singh wrote:
> 
>> We discussed the struct page size issue at VM summit. If I remember
>> correctly, Linus suggested that we consider using pfn's instead of
>> pointers for pointer members in struct page.
> 
> How would that save any memory? On a system with 16TB memory and 4k page 
> size you have at least 4 billion pfns which is the max that an unsigned 
> int can handle. If the virtual address space is sparse or larger (like on 
> IA64) then you need to use an int with more than 32 bit anyways.

Because nobody (sane) has 16TB of memory? ;-)

M.

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  reply	other threads:[~2007-09-12 19:12 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-12  2:43 KAMEZAWA Hiroyuki
2007-09-12  2:45 ` [RFC][PATCH] overwride page->mapping [1/3] cleanup KAMEZAWA Hiroyuki
2007-09-12  2:47 ` [RFC][PATCH] overwride page->mapping [2/3] page_mapping_info KAMEZAWA Hiroyuki
2007-09-12  2:48 ` [RFC][PATCH] override page->mapping [3/3] mlock counter per page KAMEZAWA Hiroyuki
2007-09-12  8:42 ` [RFC][PATCH] overwride page->mapping [0/3] intro Balbir Singh
2007-09-12 13:28   ` KAMEZAWA Hiroyuki
2007-09-12 19:10   ` Christoph Lameter
2007-09-12 19:12     ` Martin Bligh [this message]
2007-09-12 19:17       ` Christoph Lameter
2007-09-13  0:32       ` KAMEZAWA Hiroyuki
2007-09-13  1:05         ` Christoph Lameter
2007-09-13  1:27           ` KAMEZAWA Hiroyuki

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