From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759492Ab0KRQIS (ORCPT ); Thu, 18 Nov 2010 11:08:18 -0500 Received: from gir.skynet.ie ([193.1.99.77]:55411 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759428Ab0KRQIP (ORCPT ); Thu, 18 Nov 2010 11:08:15 -0500 Date: Thu, 18 Nov 2010 16:08:01 +0000 From: Mel Gorman To: Andrea Arcangeli Cc: linux-mm@kvack.org, Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, Marcelo Tosatti , Adam Litke , Avi Kivity , Hugh Dickins , Rik van Riel , Dave Hansen , Benjamin Herrenschmidt , Ingo Molnar , Mike Travis , KAMEZAWA Hiroyuki , Christoph Lameter , Chris Wright , bpicco@redhat.com, KOSAKI Motohiro , Balbir Singh , "Michael S. Tsirkin" , Peter Zijlstra , Johannes Weiner , Daisuke Nishimura , Chris Mason , Borislav Petkov Subject: Re: [PATCH 45 of 66] remove PG_buddy Message-ID: <20101118160801.GA8135@csn.ul.ie> References: <85c897773782cdde8b69.1288798100@v2.random> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <85c897773782cdde8b69.1288798100@v2.random> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 03, 2010 at 04:28:20PM +0100, Andrea Arcangeli wrote: > From: Andrea Arcangeli > > PG_buddy can be converted to _mapcount == -2. So the PG_compound_lock can be > added to page->flags without overflowing (because of the sparse section bits > increasing) with CONFIG_X86_PAE=y and CONFIG_X86_PAT=y. This also has to move > the memory hotplug code from _mapcount to lru.next to avoid any risk of > clashes. We can't use lru.next for PG_buddy removal, but memory hotplug can use > lru.next even more easily than the mapcount instead. > Does this make much of a difference? I confess I didn't read the patch closely because I didn't get the motivation. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 5FB136B004A for ; Thu, 18 Nov 2010 11:08:17 -0500 (EST) Date: Thu, 18 Nov 2010 16:08:01 +0000 From: Mel Gorman Subject: Re: [PATCH 45 of 66] remove PG_buddy Message-ID: <20101118160801.GA8135@csn.ul.ie> References: <85c897773782cdde8b69.1288798100@v2.random> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <85c897773782cdde8b69.1288798100@v2.random> Sender: owner-linux-mm@kvack.org To: Andrea Arcangeli Cc: linux-mm@kvack.org, Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, Marcelo Tosatti , Adam Litke , Avi Kivity , Hugh Dickins , Rik van Riel , Dave Hansen , Benjamin Herrenschmidt , Ingo Molnar , Mike Travis , KAMEZAWA Hiroyuki , Christoph Lameter , Chris Wright , bpicco@redhat.com, KOSAKI Motohiro , Balbir Singh , "Michael S. Tsirkin" , Peter Zijlstra , Johannes Weiner , Daisuke Nishimura , Chris Mason , Borislav Petkov List-ID: On Wed, Nov 03, 2010 at 04:28:20PM +0100, Andrea Arcangeli wrote: > From: Andrea Arcangeli > > PG_buddy can be converted to _mapcount == -2. So the PG_compound_lock can be > added to page->flags without overflowing (because of the sparse section bits > increasing) with CONFIG_X86_PAE=y and CONFIG_X86_PAT=y. This also has to move > the memory hotplug code from _mapcount to lru.next to avoid any risk of > clashes. We can't use lru.next for PG_buddy removal, but memory hotplug can use > lru.next even more easily than the mapcount instead. > Does this make much of a difference? I confess I didn't read the patch closely because I didn't get the motivation. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org