From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756565AbYA3WUp (ORCPT ); Wed, 30 Jan 2008 17:20:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750969AbYA3WUh (ORCPT ); Wed, 30 Jan 2008 17:20:37 -0500 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:57161 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751386AbYA3WUh (ORCPT ); Wed, 30 Jan 2008 17:20:37 -0500 Date: Wed, 30 Jan 2008 16:20:35 -0600 From: Robin Holt To: Christoph Lameter Cc: Jack Steiner , Andrea Arcangeli , Robin Holt , Avi Kivity , Izik Eidus , Nick Piggin , kvm-devel@lists.sourceforge.net, Benjamin Herrenschmidt , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com, Hugh Dickins Subject: Re: [patch 1/6] mmu_notifier: Core code Message-ID: <20080130222035.GX26420@sgi.com> References: <20080130022909.677301714@sgi.com> <20080130022944.236370194@sgi.com> <20080130153749.GN7233@v2.random> <20080130155306.GA13746@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 30, 2008 at 11:19:28AM -0800, Christoph Lameter wrote: > On Wed, 30 Jan 2008, Jack Steiner wrote: > > > Moving to a different lock solves the problem. > > Well it gets us back to the issue why we removed the lock. As Robin said > before: If its global then we can have a huge number of tasks contending > for the lock on startup of a process with a large number of ranks. The > reason to go to mmap_sem was that it was placed in the mm_struct and so we > would just have a couple of contentions per mm_struct. > > I'll be looking for some other way to do this. I think Andrea's original concept of the lock in the mmu_notifier_head structure was the best. I agree with him that it should be a spinlock instead of the rw_lock. Thanks, Robin From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Holt Subject: Re: [patch 1/6] mmu_notifier: Core code Date: Wed, 30 Jan 2008 16:20:35 -0600 Message-ID: <20080130222035.GX26420@sgi.com> References: <20080130022909.677301714@sgi.com> <20080130022944.236370194@sgi.com> <20080130153749.GN7233@v2.random> <20080130155306.GA13746@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Nick Piggin , Andrea Arcangeli , Peter Zijlstra , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Benjamin Herrenschmidt , Jack Steiner , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Avi Kivity , kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, daniel.blueman-xqY44rlHlBpWk0Htik3J/w@public.gmane.org, Robin Holt , Hugh Dickins 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 Wed, Jan 30, 2008 at 11:19:28AM -0800, Christoph Lameter wrote: > On Wed, 30 Jan 2008, Jack Steiner wrote: > > > Moving to a different lock solves the problem. > > Well it gets us back to the issue why we removed the lock. As Robin said > before: If its global then we can have a huge number of tasks contending > for the lock on startup of a process with a large number of ranks. The > reason to go to mmap_sem was that it was placed in the mm_struct and so we > would just have a couple of contentions per mm_struct. > > I'll be looking for some other way to do this. I think Andrea's original concept of the lock in the mmu_notifier_head structure was the best. I agree with him that it should be a spinlock instead of the rw_lock. Thanks, Robin ------------------------------------------------------------------------- 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: Wed, 30 Jan 2008 16:20:35 -0600 From: Robin Holt Subject: Re: [patch 1/6] mmu_notifier: Core code Message-ID: <20080130222035.GX26420@sgi.com> References: <20080130022909.677301714@sgi.com> <20080130022944.236370194@sgi.com> <20080130153749.GN7233@v2.random> <20080130155306.GA13746@sgi.com> 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: Jack Steiner , Andrea Arcangeli , Robin Holt , Avi Kivity , Izik Eidus , Nick Piggin , kvm-devel@lists.sourceforge.net, Benjamin Herrenschmidt , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com, Hugh Dickins List-ID: On Wed, Jan 30, 2008 at 11:19:28AM -0800, Christoph Lameter wrote: > On Wed, 30 Jan 2008, Jack Steiner wrote: > > > Moving to a different lock solves the problem. > > Well it gets us back to the issue why we removed the lock. As Robin said > before: If its global then we can have a huge number of tasks contending > for the lock on startup of a process with a large number of ranks. The > reason to go to mmap_sem was that it was placed in the mm_struct and so we > would just have a couple of contentions per mm_struct. > > I'll be looking for some other way to do this. I think Andrea's original concept of the lock in the mmu_notifier_head structure was the best. I agree with him that it should be a spinlock instead of the rw_lock. Thanks, Robin -- 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