From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262217AbVBBDQe (ORCPT ); Tue, 1 Feb 2005 22:16:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262255AbVBBDPa (ORCPT ); Tue, 1 Feb 2005 22:15:30 -0500 Received: from smtp012.mail.yahoo.com ([216.136.173.32]:50053 "HELO smtp012.mail.yahoo.com") by vger.kernel.org with SMTP id S262250AbVBBDJo (ORCPT ); Tue, 1 Feb 2005 22:09:44 -0500 Subject: Re: page fault scalability patch V16 [3/4]: Drop page_table_lock in handle_mm_fault From: Nick Piggin To: Christoph Lameter Cc: Andi Kleen , Andrew Morton , torvalds@osdl.org, hugh@veritas.com, linux-mm@kvack.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, benh@kernel.crashing.org In-Reply-To: References: <41E5B7AD.40304@yahoo.com.au> <41E5BC60.3090309@yahoo.com.au> <20050113031807.GA97340@muc.de> <20050113180205.GA17600@muc.de> <20050114043944.GB41559@muc.de> <20050114170140.GB4634@muc.de> <41FF00CE.8060904@yahoo.com.au> <1107304296.5131.13.camel@npiggin-nld.site> <1107308498.5131.28.camel@npiggin-nld.site> Content-Type: text/plain Date: Wed, 02 Feb 2005 14:09:37 +1100 Message-Id: <1107313778.5131.32.camel@npiggin-nld.site> Mime-Version: 1.0 X-Mailer: Evolution 2.0.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2005-02-01 at 18:49 -0800, Christoph Lameter wrote: > On Wed, 2 Feb 2005, Nick Piggin wrote: > > > Well yeah, but the interesting case is when that isn't a lock ;) > > > > I'm not saying what you've got is no good. I'm sure it would be fine > > for testing. And if it happens that we can do the "page_count doesn't > > mean anything after it has reached zero and been freed. Nor will it > > necessarily be zero when a new page is allocated" thing without many > > problems, then this may be a fine way to do it. > > > > I was just pointing out this could be a problem without putting a > > lot of thought into it... > > Surely we need to do this the right way. Do we really need to > use page_cache_get()? Is anything relying on page_count == 2 of > the old_page? > > I mean we could just speculatively copy, risk copying crap and > discard that later when we find that the pte has changed. This would > simplify the function: > I think this may be the better approach. Anyone else? Find local movie times and trailers on Yahoo! Movies. http://au.movies.yahoo.com