Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765486AbYBMA54 (ORCPT ); Tue, 12 Feb 2008 19:57:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1765355AbYBMA5Y (ORCPT ); Tue, 12 Feb 2008 19:57:24 -0500 Received: from relay2.sgi.com ([192.48.171.30]:50960 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758706AbYBMA5U (ORCPT ); Tue, 12 Feb 2008 19:57:20 -0500 Date: Tue, 12 Feb 2008 16:57:19 -0800 (PST) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Felix Marti cc: Roland Dreier , Rik van Riel , steiner@sgi.com, Andrea Arcangeli , a.p.zijlstra@chello.nl, izike@qumranet.com, linux-kernel@vger.kernel.org, avi@qumranet.com, linux-mm@kvack.org, daniel.blueman@quadrics.com, Robin Holt , general@lists.openfabrics.org, Andrew Morton , kvm-devel@lists.sourceforge.net Subject: RE: [ofa-general] Re: Demand paging for memory regions In-Reply-To: <8A71B368A89016469F72CD08050AD334026D5C23@maui.asicdesigners.com> Message-ID: References: <20080208234302.GH26564@sgi.com><20080208155641.2258ad2c.akpm@linux-foundation.org><20080209012446.GB7051@v2.random><20080209015659.GC7051@v2.random><20080209075556.63062452@bree.surriel.com><47B2174E.5000708@opengridcomputing.com> <8A71B368A89016469F72CD08050AD334026D5C23@maui.asicdesigners.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1210 Lines: 23 On Tue, 12 Feb 2008, Felix Marti wrote: > > I don't know anything about the T3 internals, but it's not clear that > > you could do this without a new chip design in general. Lot's of RDMA > > devices were designed expecting that when a packet arrives, the HW can > > look up the bus address for a given memory region/offset and place the > > packet immediately. It seems like a major change to be able to > > generate a "page fault" interrupt when a page isn't present, or even > > just wait to scatter some data until the host finishes updating page > > tables when the HW needs the translation. > > That is correct, not a change we can make for T3. We could, in theory, > deal with changing mappings though. The change would need to be > synchronized though: the VM would need to tell us which mapping were > about to change and the driver would then need to disable DMA to/from > it, do the change and resume DMA. Right. That is the intend of the patchset. -- 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/