Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757915AbYBOSqN (ORCPT ); Fri, 15 Feb 2008 13:46:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756601AbYBOSp6 (ORCPT ); Fri, 15 Feb 2008 13:45:58 -0500 Received: from relay2.sgi.com ([192.48.171.30]:57317 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756159AbYBOSp5 (ORCPT ); Fri, 15 Feb 2008 13:45:57 -0500 Date: Fri, 15 Feb 2008 10:45:55 -0800 (PST) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Caitlin Bestler cc: linux-kernel@vger.kernel.org, avi@qumranet.com, linux-mm@kvack.org, general@lists.openfabrics.org, kvm-devel@lists.sourceforge.net Subject: RE: [ofa-general] Re: Demand paging for memory regions In-Reply-To: <78C9135A3D2ECE4B8162EBDCE82CAD77030E25BA@nekter> Message-ID: References: <47B2174E.5000708@opengridcomputing.com> <8A71B368A89016469F72CD08050AD334026D5C23@maui.asicdesigners.com> <47B45994.7010805@opengridcomputing.com> <469958e00802141217i3a3d16a1k1232d69b8ba54471@mail.gmail.com> <469958e00802141443g33448abcs3efa6d6c4aec2b56@mail.gmail.com> <78C9135A3D2ECE4B8162EBDCE82CAD77030E2456@nekter> <78C9135A3D2ECE4B8162EBDCE82CAD77030E25BA@nekter> 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: 1257 Lines: 31 On Fri, 15 Feb 2008, Caitlin Bestler wrote: > > What does it mean that the "application layer has to be determine what > > pages are registered"? The application does not know which of its > pages > > are currently in memory. It can only force these pages to stay in > > memory if their are mlocked. > > > > An application that advertises an RDMA accessible buffer > to a remote peer *does* have to know that its pages *are* > currently in memory. Ok that would mean it needs to inform the VM of that issue by mlocking these pages. > But the more fundamental issue is recognizing that applications > that use direct interfaces need to know that buffers that they > enable truly have committed resources. They need a way to > ask for twenty *real* pages, not twenty pages of address > space. And they need to do it in a way that allows memory > to be rearranged or even migrated with them to a new host. mlock will force the pages to stay in memory without requiring the OS to keep them where they are. -- 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/