From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757947AbYBIB5R (ORCPT ); Fri, 8 Feb 2008 20:57:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755395AbYBIB5G (ORCPT ); Fri, 8 Feb 2008 20:57:06 -0500 Received: from host36-195-149-62.serverdedicati.aruba.it ([62.149.195.36]:56940 "EHLO mx.cpushare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754508AbYBIB5F (ORCPT ); Fri, 8 Feb 2008 20:57:05 -0500 Date: Sat, 9 Feb 2008 02:56:59 +0100 From: Andrea Arcangeli To: Christoph Lameter Cc: Roland Dreier , a.p.zijlstra@chello.nl, izike@qumranet.com, steiner@sgi.com, linux-kernel@vger.kernel.org, avi@qumranet.com, linux-mm@kvack.org, daniel.blueman@quadrics.com, Robin Holt , general@lists.openfabrics.org, Andrew Morton , kvm-devel@lists.sourceforge.net, Rik van Riel Subject: Re: [ofa-general] Re: [patch 0/6] MMU Notifiers V6 Message-ID: <20080209015659.GC7051@v2.random> References: <20080208234302.GH26564@sgi.com> <20080208155641.2258ad2c.akpm@linux-foundation.org> <20080209012446.GB7051@v2.random> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 08, 2008 at 05:27:03PM -0800, Christoph Lameter wrote: > Pages will still be on the LRU and cycle through rmap again and again. > If page migration is used on those pages then the code may make repeated > attempt to migrate the page thinking that the page count must at some > point drop. > > I do not think that the page count was intended to be used to pin pages > permanently. If we had a marker on such pages then we could take them off > the LRU and not try to migrate them. The VM shouldn't break if try_to_unmap doesn't actually make the page freeable for whatever reason. Permanent pins shouldn't happen anyway, so defining an ad-hoc API for that doesn't sound too appealing. Not sure if old hardware deserves those special lru-size-reduction optimizations but it's not my call (certainly swapoff/mlock would get higher priority in that lru-size-reduction area). From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: Re: [ofa-general] Re: [patch 0/6] MMU Notifiers V6 Date: Sat, 9 Feb 2008 02:56:59 +0100 Message-ID: <20080209015659.GC7051@v2.random> References: <20080208234302.GH26564@sgi.com> <20080208155641.2258ad2c.akpm@linux-foundation.org> <20080209012446.GB7051@v2.random> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: a.p.zijlstra-/NLkJaSkS4VmR6Xm/wNWPw@public.gmane.org, Roland Dreier , steiner-sJ/iWh9BUns@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, daniel.blueman-xqY44rlHlBpWk0Htik3J/w@public.gmane.org, Robin Holt , general-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org, Andrew Morton , kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Christoph Lameter Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org On Fri, Feb 08, 2008 at 05:27:03PM -0800, Christoph Lameter wrote: > Pages will still be on the LRU and cycle through rmap again and again. > If page migration is used on those pages then the code may make repeated > attempt to migrate the page thinking that the page count must at some > point drop. > > I do not think that the page count was intended to be used to pin pages > permanently. If we had a marker on such pages then we could take them off > the LRU and not try to migrate them. The VM shouldn't break if try_to_unmap doesn't actually make the page freeable for whatever reason. Permanent pins shouldn't happen anyway, so defining an ad-hoc API for that doesn't sound too appealing. Not sure if old hardware deserves those special lru-size-reduction optimizations but it's not my call (certainly swapoff/mlock would get higher priority in that lru-size-reduction area). ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 9 Feb 2008 02:56:59 +0100 From: Andrea Arcangeli Subject: Re: [ofa-general] Re: [patch 0/6] MMU Notifiers V6 Message-ID: <20080209015659.GC7051@v2.random> References: <20080208234302.GH26564@sgi.com> <20080208155641.2258ad2c.akpm@linux-foundation.org> <20080209012446.GB7051@v2.random> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Roland Dreier , a.p.zijlstra@chello.nl, izike@qumranet.com, steiner@sgi.com, linux-kernel@vger.kernel.org, avi@qumranet.com, linux-mm@kvack.org, daniel.blueman@quadrics.com, Robin Holt , general@lists.openfabrics.org, Andrew Morton , kvm-devel@lists.sourceforge.net, Rik van Riel List-ID: On Fri, Feb 08, 2008 at 05:27:03PM -0800, Christoph Lameter wrote: > Pages will still be on the LRU and cycle through rmap again and again. > If page migration is used on those pages then the code may make repeated > attempt to migrate the page thinking that the page count must at some > point drop. > > I do not think that the page count was intended to be used to pin pages > permanently. If we had a marker on such pages then we could take them off > the LRU and not try to migrate them. The VM shouldn't break if try_to_unmap doesn't actually make the page freeable for whatever reason. Permanent pins shouldn't happen anyway, so defining an ad-hoc API for that doesn't sound too appealing. Not sure if old hardware deserves those special lru-size-reduction optimizations but it's not my call (certainly swapoff/mlock would get higher priority in that lru-size-reduction area). -- 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