From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: [ofa-general] Re: [PATCH] mmu notifiers #v8 Date: Mon, 3 Mar 2008 13:51:53 +0100 Message-ID: <20080303125152.GS8091@v2.random> References: <20080219135851.GI7128@v2.random> <20080219231157.GC18912@wotan.suse.de> <20080220010941.GR7128@v2.random> <20080220103942.GU7128@v2.random> <20080221045430.GC15215@wotan.suse.de> <20080221144023.GC9427@v2.random> <20080221161028.GA14220@sgi.com> <20080227192610.GF28483@v2.random> <20080302155457.GK8091@v2.random> <20080303032934.GA3301@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Peter Zijlstra , linux-mm@kvack.org, Izik Eidus , Kanoj Sarcar , Roland Dreier , Jack Steiner , linux-kernel@vger.kernel.org, Avi Kivity , kvm-devel@lists.sourceforge.net, daniel.blueman@quadrics.com, Robin Holt , general@lists.openfabrics.org, akpm@linux-foundation.org, Christoph Lameter To: Nick Piggin Return-path: Content-Disposition: inline In-Reply-To: <20080303032934.GA3301@wotan.suse.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: general-bounces@lists.openfabrics.org Errors-To: general-bounces@lists.openfabrics.org List-Id: kvm.vger.kernel.org On Mon, Mar 03, 2008 at 04:29:34AM +0100, Nick Piggin wrote: > to something I prefer. Others may not, but I'll post them for debate > anyway. Sure, thanks! > > I didn't drop invalidate_page, because invalidate_range_begin/end > > would be slower for usages like KVM/GRU (we don't need a begin/end > > there because where invalidate_page is called, the VM holds a > > reference on the page). do_wp_page should also use invalidate_page > > since it can free the page after dropping the PT lock without losing > > any performance (that's not true for the places where invalidate_range > > is called). > > I'm still not completely happy with this. I had a very quick look > at the GRU driver, but I don't see why it can't be implemented > more like the regular TLB model, and have TLB insertions depend on > the linux pte, and do invalidates _after_ restricting permissions > to the pte. > > Ie. I'd still like to get rid of invalidate_range_begin, and get > rid of invalidate calls from places where permissions are relaxed. _begin exists because by the time _end is called, the VM already dropped the reference on the page. This way we can do a single invalidate no matter how large the range is. I don't see ways to remove _begin while still invoking _end a single time for the whole range. > If we can agree on the API, then I don't see any reason why it can't > go into 2.6.25, unless someome wants more time to review it (but > 2.6.25 release should be quite far away still so there should be quite > a bit of time). Cool! ;)