From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 26 Feb 2008 06:28:50 -0600 From: Robin Holt Subject: Re: [ofa-general] Re: [patch 5/6] mmu_notifier: Support for drivers with revers maps (f.e. for XPmem) Message-ID: <20080226122850.GP11391@sgi.com> References: <20080215064859.384203497@sgi.com> <200802261711.33213.nickpiggin@yahoo.com.au> <20080226072137.GD26611@minantech.com> <200802261952.42567.nickpiggin@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200802261952.42567.nickpiggin@yahoo.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Gleb Natapov , Robin Holt , steiner@sgi.com, Andrea Arcangeli , Peter Zijlstra , linux-mm@kvack.org, Izik Eidus , Kanoj Sarcar , Roland Dreier , linux-kernel@vger.kernel.org, Avi Kivity , kvm-devel@lists.sourceforge.net, daniel.blueman@quadrics.com, general@lists.openfabrics.org, akpm@linux-foundation.org, Christoph Lameter List-ID: On Tue, Feb 26, 2008 at 07:52:41PM +1100, Nick Piggin wrote: > On Tuesday 26 February 2008 18:21, Gleb Natapov wrote: > > On Tue, Feb 26, 2008 at 05:11:32PM +1100, Nick Piggin wrote: > > > > You are missing one point here. The MPI specifications that have > > > > been out there for decades do not require the process use a library > > > > for allocating the buffer. I realize that is a horrible shortcoming, > > > > but that is the world we live in. Even if we could change that spec, > > > > > > Can you change the spec? > > > > Not really. It will break all existing codes. > > I meant as in eg. submit changes to MPI-3 > > > > MPI-2 provides a call for > > memory allocation (and it's beneficial to use this call for some > > interconnects), but many (most?) applications are still written for MPI-1 > > and those that are written for MPI-2 mostly uses the old habit of > > allocating memory by malloc(), or even use stack or BSS memory for > > communication buffer purposes. > > OK, so MPI-2 already has some way to do that... I'm not saying that we > can now completely dismiss the idea of using notifiers for this, but it > is just a good data point to know. It is in MPI-2, but MPI-2 does not prohibit communication from regions not allocated by the MPI call. 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