From mboxrd@z Thu Jan  1 00:00:00 1970
From: Robin Holt <holt@sgi.com>
Subject: [ofa-general] Re: [patch] my mmu notifiers
Date: Tue, 19 Feb 2008 20:46:03 -0600
Message-ID: <20080220024602.GA11364@sgi.com>
References: <20080219084357.GA22249@wotan.suse.de>
	<20080219135851.GI7128@v2.random> <20080219142725.GA23200@sgi.com>
	<20080219230427.GB18912@wotan.suse.de>
	<20080220005206.GP7128@v2.random>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Nick Piggin <npiggin@suse.de>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
	linux-mm@kvack.org, Izik Eidus <izike@qumranet.com>,
	Kanoj Sarcar <kanojsarcar@yahoo.com>, Roland Dreier <rdreier@cisco.com>,
	Jack Steiner <steiner@sgi.com>, linux-kernel@vger.kernel.org,
	Avi Kivity <avi@qumranet.com>, kvm-devel@lists.sourceforge.net,
	daniel.blueman@quadrics.com, Robin Holt <holt@sgi.com>,
	general@lists.openfabrics.org, akpm@linux-foundation.org,
	Christoph Lameter <clameter@sgi.com>
To: Andrea Arcangeli <andrea@qumranet.com>
Return-path: <general-bounces@lists.openfabrics.org>
Content-Disposition: inline
In-Reply-To: <20080220005206.GP7128@v2.random>
List-Unsubscribe: <http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general>,
	<mailto:general-request@lists.openfabrics.org?subject=unsubscribe>
List-Archive: <http://lists.openfabrics.org/pipermail/general>
List-Post: <mailto:general@lists.openfabrics.org>
List-Help: <mailto:general-request@lists.openfabrics.org?subject=help>
List-Subscribe: <http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general>,
	<mailto:general-request@lists.openfabrics.org?subject=subscribe>
Sender: general-bounces@lists.openfabrics.org
Errors-To: general-bounces@lists.openfabrics.org
List-Id: kvm.vger.kernel.org

On Wed, Feb 20, 2008 at 01:52:06AM +0100, Andrea Arcangeli wrote:
> On Wed, Feb 20, 2008 at 12:04:27AM +0100, Nick Piggin wrote:
> > OK (thanks to Robin as well). Now I understand why you are using it,
> > but I don't understand why you don't defer new TLBs after the point
> > where the linux pte changes. If you can do that, then you look and
> > act much more like a TLB from the point of view of the Linux vm.
> 
> Christoph was forced to put the invalidate_range callback _after_
> dropping the PT lock because xpmem has to wait I/O there. But
> invalidate_range is called after freeing the VM reference on the pages
> so then GRU needed a _range_begin too because GRU has to flush the tlb
> before the VM reference on the page is released (xpmem and KVM pin the
> pages mapped by the secondary mmu, GRU doesn't). So then
> invalidate_range was renamed to invalidate_range_end.

Currently, xpmem blocks faults for the range specified at the _begin
callout, then shoots down remote TLBs and does the put_page for all the
pages in the specified range.  The _end callout merely removes the block.
We do not do any wait for I/O.  By the time we return from the _begin
callout, all activity by the remotes is stopped, pages are dereferenced,
and future faults are blocked until released by the _end callout.

Thanks,
Robin