Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754713AbYBSL7w (ORCPT ); Tue, 19 Feb 2008 06:59:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751494AbYBSL7o (ORCPT ); Tue, 19 Feb 2008 06:59:44 -0500 Received: from relay2.sgi.com ([192.48.171.30]:58599 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751301AbYBSL7n (ORCPT ); Tue, 19 Feb 2008 06:59:43 -0500 Date: Tue, 19 Feb 2008 05:59:38 -0600 From: Robin Holt To: Nick Piggin Cc: akpm@linux-foundation.org, Andrea Arcangeli , Robin Holt , Avi Kivity , Izik Eidus , kvm-devel@lists.sourceforge.net, Peter Zijlstra , general@lists.openfabrics.org, Steve Wise , Roland Dreier , Kanoj Sarcar , steiner@sgi.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com, Christoph Lameter Subject: Re: [patch] my mmu notifiers Message-ID: <20080219115938.GD11391@sgi.com> References: <20080219084357.GA22249@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080219084357.GA22249@wotan.suse.de> 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 Content-Length: 1439 Lines: 27 On Tue, Feb 19, 2008 at 09:43:57AM +0100, Nick Piggin wrote: > So I implemented mmu notifiers slightly differently. Andrea's mmu notifiers > are rather similar. However I have tried to make a point of minimising the > impact the the core mm/. I don't see why we need to invalidate or flush > anything when changing the pte to be _more_ permissive, and I don't > understand the need for invalidate_begin/invalidate_end pairs at all. > What I have done is basically create it so that the notifiers get called > basically in the same place as the normal TLB flushing is done, and nowhere > else. Because XPMEM needs to be able to sleep during its callout. For that, we need to move this outside of the page table lock and suddenly we need the begin/end pair again. There was considerable discussion about this exact point numerous times. We tried to develop the most inclusive design possible. Our design would even be extendable to IB, assuming they made some very disruptive changes to their MPI and communication libraries. IB would suffer the same problems XPMEM does in that the TLB entries need to be removed on a remote host which is operating completely independently. Thanks, Robin -- 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/