From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763484AbYBTArR (ORCPT ); Tue, 19 Feb 2008 19:47:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752511AbYBTArC (ORCPT ); Tue, 19 Feb 2008 19:47:02 -0500 Received: from host36-195-149-62.serverdedicati.aruba.it ([62.149.195.36]:44559 "EHLO mx.cpushare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752491AbYBTArA (ORCPT ); Tue, 19 Feb 2008 19:47:00 -0500 Date: Wed, 20 Feb 2008 01:46:35 +0100 From: Andrea Arcangeli To: Nick Piggin Cc: akpm@linux-foundation.org, 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: <20080220004635.GO7128@v2.random> References: <20080219084357.GA22249@wotan.suse.de> <20080219135851.GI7128@v2.random> <20080219225923.GA18912@wotan.suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080219225923.GA18912@wotan.suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 19, 2008 at 11:59:23PM +0100, Nick Piggin wrote: > That's why I don't understand the need for the pairs: it should be > done like this. Yes, except it can't be done like this for xpmem. > OK, I didn't see the invalidate_pages call... See the last patch I posted to Andrew, you've probably looked at the old patches, the old patches didn't work for GRU and didn't work for xpmem and they weren't optimized to cluster the invalidates for each 4k-large-pte. > I thought that could be used by a non-sleeping user (not intending > to try supporting sleeping users). If it is useless then it should > go away (BTW. I didn't see your recent patch, some of my confusion > I think stems from Christoph's novel way of merging and splitting > patches). I kept improving my patch in case the VM maintainers would consider xpmem requirements not workable from a linux-VM point of view, and they preferred to have something obviously safe, strightforward and non intrusive, despite it doesn't support the only sleeping user out there I know of (xpmem). My patch supports KVM and GRU (and any other not sleeping user). > > No idea why xpmem needs range_begin, I perfectly understand why GRU > > needs _begin with Chrisotph's patch (gru lacks the page pin) but I > > dunno why xpmem needs range_begin (xpmem has the page pin so I also > > think it could avoid using range_begin). Still to support GRU you need > > both to call invalidate_range in places that can sleep and you need > > the external rmap notifier. The moment you add xpmem into the equation > > your and my clean patches become Christoph's one... > > Sorry, I kind of didn't have time to follow the conversation so well > before; are there patches posted for gru and/or xpmem? There's some xpmem code posted but the posted one isn't using the mmu notifiers yet. GRU code may be available from Jack. I only know for sure their requirements in terms of mmu notifiers.