Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753592Ab0AGXwX (ORCPT ); Thu, 7 Jan 2010 18:52:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753476Ab0AGXwW (ORCPT ); Thu, 7 Jan 2010 18:52:22 -0500 Received: from mx1.redhat.com ([209.132.183.28]:28950 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753471Ab0AGXwV (ORCPT ); Thu, 7 Jan 2010 18:52:21 -0500 Message-ID: <4B467388.809@redhat.com> Date: Thu, 07 Jan 2010 18:51:36 -0500 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Lightning/1.0pre Thunderbird/3.0 MIME-Version: 1.0 To: Linus Torvalds CC: Peter Zijlstra , Christoph Lameter , Arjan van de Ven , "Paul E. McKenney" , KAMEZAWA Hiroyuki , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "minchan.kim@gmail.com" , "hugh.dickins" , Nick Piggin , Ingo Molnar Subject: Re: [RFC][PATCH 6/8] mm: handle_speculative_fault() References: <20100104182429.833180340@chello.nl> <20100104182813.753545361@chello.nl> <20100105054536.44bf8002@infradead.org> <20100105192243.1d6b2213@infradead.org> <1262884960.4049.106.camel@laptop> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1087 Lines: 28 On 01/07/2010 12:36 PM, Linus Torvalds wrote: > On Thu, 7 Jan 2010, Peter Zijlstra wrote: >> >> Right, supposing we can make this speculative fault stuff work, then we >> can basically reduce the mmap_sem usage in fault to: >> >> - allocating new page tables >> - extending the growable vmas >> >> And do everything else without holding it, including zeroing and IO. > > Well, I have yet to hear a realistic scenario of _how_ to do it all > speculatively in the first place, at least not without horribly subtle > complexity issues. So I'd really rather see how far we can possibly get by > just improving mmap_sem. I would like to second this sentiment. I am trying to make the anon_vma and rmap bits more scalable for multi-process server workloads and it is quite worrying how complex locking already is. -- All rights reversed. -- 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/