From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 13 Sep 2007 09:32:03 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC][PATCH] overwride page->mapping [0/3] intro Message-Id: <20070913093203.841b76a7.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <46E83A19.2090604@google.com> References: <20070912114322.e4d8a86e.kamezawa.hiroyu@jp.fujitsu.com> <46E7A666.7080409@linux.vnet.ibm.com> <46E83A19.2090604@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Martin Bligh Cc: Christoph Lameter , Balbir Singh , "linux-mm@kvack.org" , "nickpiggin@yahoo.com.au" , "Lee.Schermerhorn@hp.com" , Andrew Morton List-ID: On Wed, 12 Sep 2007 12:12:25 -0700 Martin Bligh wrote: > 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? ;-) > I think it's not problem of size of memory. It's problem of size of address space, 64 bit. Some machine may have very sparse address configuration from unknown(insane) reason. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org