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/