From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx142.postini.com [74.125.245.142]) by kanga.kvack.org (Postfix) with SMTP id A102C6B0044 for ; Tue, 14 Aug 2012 17:37:34 -0400 (EDT) Date: Wed, 15 Aug 2012 00:38:32 +0300 From: "Michael S. Tsirkin" Subject: Re: [PATCH v7 2/4] virtio_balloon: introduce migration primitives to balloon pages Message-ID: <20120814213832.GA29180@redhat.com> References: <20120813084123.GF14081@redhat.com> <20120814182244.GB13338@t510.redhat.com> <20120814195139.GA28870@redhat.com> <20120814195916.GC28870@redhat.com> <20120814200830.GD22133@t510.redhat.com> <20120814202401.GB28990@redhat.com> <20120814202949.GF22133@t510.redhat.com> <20120814204906.GD28990@redhat.com> <20120814205426.GA29162@redhat.com> <502ABB9B.90108@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <502ABB9B.90108@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Rafael Aquini , linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Rusty Russell , Mel Gorman , Andi Kleen , Andrew Morton , Konrad Rzeszutek Wilk , Minchan Kim On Tue, Aug 14, 2012 at 04:56:59PM -0400, Rik van Riel wrote: > On 08/14/2012 04:54 PM, Michael S. Tsirkin wrote: > > >To clarify, the global state that this patch adds, is ugly > >even if we didn't support multiple balloons yet. > >So I don't think I can accept such a patch. > >Rusty has a final word here, maybe he thinks differently. > > Before deciding that "does not support multiple balloon drivers > at once" is an issue, is there any use case at all for having > multiple balloon drivers active at a time? > > I do not see any. For example, we had a proposal for a page-cache backed device. So it could be useful to have two, a regular balloon and a pagecache backed one. There could be other uses - it certainly looks like it works so how can you be sure it's useless? And even ignoring that, global pointer to a device is an ugly hack and ugly hacks tend to explode. And even ignoring estetics, and if we decide we are fine with a single balloon, it needs to fail gracefully not crash like it does now. > -- > All rights reversed -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org