Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753160Ab2HUXmq (ORCPT ); Tue, 21 Aug 2012 19:42:46 -0400 Received: from ozlabs.org ([203.10.76.45]:35050 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752588Ab2HUXmn (ORCPT ); Tue, 21 Aug 2012 19:42:43 -0400 From: Rusty Russell To: "Michael S. Tsirkin" , Mel Gorman Cc: Rafael Aquini , linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Rik van Riel , Andi Kleen , Andrew Morton , Konrad Rzeszutek Wilk , Minchan Kim Subject: Re: [PATCH v7 2/4] virtio_balloon: introduce migration primitives to balloon pages In-Reply-To: <20120815112851.GA2707@redhat.com> References: <20120813084123.GF14081@redhat.com> <20120814182244.GB13338@t510.redhat.com> <20120814195139.GA28870@redhat.com> <20120814201113.GE22133@t510.redhat.com> <20120815090528.GH4052@csn.ul.ie> <20120815092528.GA29214@redhat.com> <20120815094839.GJ4052@csn.ul.ie> <20120815100108.GA1999@redhat.com> <20120815111651.GL4052@csn.ul.ie> <20120815112851.GA2707@redhat.com> User-Agent: Notmuch/0.12 (http://notmuchmail.org) Emacs/23.3.1 (i686-pc-linux-gnu) Date: Tue, 21 Aug 2012 15:01:37 +0930 Message-ID: <87mx1o3j5y.fsf@rustcorp.com.au> 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: 1204 Lines: 26 On Wed, 15 Aug 2012 14:28:51 +0300, "Michael S. Tsirkin" wrote: > On Wed, Aug 15, 2012 at 12:16:51PM +0100, Mel Gorman wrote: > > I was thinking of exactly that page->mapping == balloon_mapping check. As I > > do not know how many active balloon drivers there might be I cannot guess > > in advance how much of a scalability problem it will be. > > Not at all sure multiple drivers are worth supporting, but multiple > *devices* is I think worth supporting, if for no other reason than that > they can work today. For that, we need a device pointer which Rafael > wants to put into the mapping, this means multiple balloon mappings. Rafael, please make sure that the balloon driver fails on the second and subsequent balloon devices. Michael, we only allow multiple balloon devices because it fell out of the implementation. If it causes us even the slightest issue, we should not support it. It's not a sensible setup. Cheers, Rusty. -- 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/