Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764453AbYBNWoL (ORCPT ); Thu, 14 Feb 2008 17:44:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754259AbYBNWn5 (ORCPT ); Thu, 14 Feb 2008 17:43:57 -0500 Received: from qb-out-0506.google.com ([72.14.204.238]:23362 "EHLO qb-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752108AbYBNWn4 (ORCPT ); Thu, 14 Feb 2008 17:43:56 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth; b=QsczdH+omZX8Vamnlhj1ARWgwknHIPWj5/49QocKCghDHZOdT16URK71fjrcN0Rq8bXNbIsxT3Vtn0jSG8ODghJAQnw/MQ39br7DWzzq2bYbiZrZq1eCc1F7DSBIdoHevUl668buKZ+/f/apNVm4q39Et9MEbcBV4j9GKkx3rCk= Message-ID: <469958e00802141443g33448abcs3efa6d6c4aec2b56@mail.gmail.com> Date: Thu, 14 Feb 2008 14:43:54 -0800 From: "Caitlin Bestler" To: "Christoph Lameter" Subject: Re: [ofa-general] Re: Demand paging for memory regions Cc: linux-kernel@vger.kernel.org, avi@qumranet.com, linux-mm@kvack.org, general@lists.openfabrics.org, kvm-devel@lists.sourceforge.net In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <47B2174E.5000708@opengridcomputing.com> <8A71B368A89016469F72CD08050AD334026D5C23@maui.asicdesigners.com> <47B45994.7010805@opengridcomputing.com> <469958e00802141217i3a3d16a1k1232d69b8ba54471@mail.gmail.com> X-Google-Sender-Auth: 1adaa8be58ad84cb Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1525 Lines: 31 On Thu, Feb 14, 2008 at 12:20 PM, Christoph Lameter wrote: > On Thu, 14 Feb 2008, Caitlin Bestler wrote: > > > So suspend/resume to re-arrange pages is one thing. Suspend/resume to cover > > swapping out pages so they can be reallocated is an exercise in futility. By the > > time you resume the connections will be broken or at the minimum damaged. > > The connections would then have to be torn down before swap out and would > have to be reestablished after the pages have been brought back from swap. > > I have no problem with that, as long as the application layer is responsible for tearing down and re-establishing the connections. The RDMA/transport layers are incapable of tearing down and re-establishing a connection transparently because connections need to be approved above the RDMA layer. Further the teardown will have visible artificats that the application must deal with, such as flushed Recv WQEs. This is still, the RDMA device will do X and will not worry about Y. The reasons for not worrying about Y could be that the suspend will be very short, or that other mechanisms have taken care of all the Ys independently. For example, an HPC cluster that suspended the *entire* cluster would not have to worry about dropped packets. -- 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/