From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id C01796B0044 for ; Thu, 7 Jan 2010 18:52:13 -0500 (EST) Message-ID: <4B467388.809@redhat.com> Date: Thu, 07 Jan 2010 18:51:36 -0500 From: Rik van Riel MIME-Version: 1.0 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: owner-linux-mm@kvack.org 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 List-ID: 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, 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