Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932399AbWE3UWn (ORCPT ); Tue, 30 May 2006 16:22:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932400AbWE3UWn (ORCPT ); Tue, 30 May 2006 16:22:43 -0400 Received: from omx1-ext.sgi.com ([192.48.179.11]:54148 "EHLO omx1.americas.sgi.com") by vger.kernel.org with ESMTP id S932399AbWE3UWm (ORCPT ); Tue, 30 May 2006 16:22:42 -0400 Date: Tue, 30 May 2006 13:21:52 -0700 (PDT) From: Christoph Lameter To: David Howells cc: Peter Zijlstra , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins , Andrew Morton , Christoph Lameter , Martin Bligh , Nick Piggin , Linus Torvalds Subject: Re: [PATCH 1/3] mm: tracking shared dirty pages In-Reply-To: <18903.1149011787@warthog.cambridge.redhat.com> Message-ID: References: <20060525135534.20941.91650.sendpatchset@lappy> <20060525135555.20941.36612.sendpatchset@lappy> <24747.1148653985@warthog.cambridge.redhat.com> <12042.1148976035@warthog.cambridge.redhat.com> <7966.1149006374@warthog.cambridge.redhat.com> <18903.1149011787@warthog.cambridge.redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1455 Lines: 34 On Tue, 30 May 2006, David Howells wrote: > Christoph Lameter wrote: > > > On Tue, 30 May 2006, David Howells wrote: > > > > > > If set_page_dirty cannot reserve the page then we know that some severe > > > > action is required. The FS method set_page_dirty() could: > > > > > > But by the time set_page_dirty() is called, it's too late as the code > > > currently stands. We've already marked the PTE writable and dirty. The > > > page_mkwrite() op is called _first_. > > > > We are in set_page_dirty and this would be part of set_page_dirty > > processing. > > Eh? What do you mean "We are in set_page_dirty"? We could do the reservation in as part of the set_page_dirty FS method. > Actually, I'm not sure that calling set_page_dirty() at the bottom of > do_wp_page() is necessarily a good idea. It's possible that the page will be > marked dirty in do_wp_page() and then will get written back before the write > actually succeeds. In other words the page may be marked dirty and cleaned up > all before the modification _actually_ occurs. On the other hand, the common > case is probably that the store instruction will beat the writeback. Yes we are aware of that case. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/