From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=41241 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OGuNF-0003JI-2v for qemu-devel@nongnu.org; Tue, 25 May 2010 09:40:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OGuLF-0001gD-2D for qemu-devel@nongnu.org; Tue, 25 May 2010 09:38:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:28764) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OGuLE-0001fy-My for qemu-devel@nongnu.org; Tue, 25 May 2010 09:38:45 -0400 Message-ID: <4BFBD2D5.2000201@redhat.com> Date: Tue, 25 May 2010 16:38:29 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm References: <20100519192222.GD61706@ncolin.muc.de> <4BF5A9D2.5080609@codemonkey.ws> <4BF91937.2070801@redhat.com> <4BFBAE46.5050801@redhat.com> <4BFBB3C1.9020905@redhat.com> <4BFBCFAC.9070807@codemonkey.ws> <4BFBD13C.60605@redhat.com> <4BFBD20E.5060207@codemonkey.ws> In-Reply-To: <4BFBD20E.5060207@codemonkey.ws> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Kevin Wolf , kvm@vger.kernel.org, qemu-devel@nongnu.org, Blue Swirl , ceph-devel@vger.kernel.org, Christian Brunner On 05/25/2010 04:35 PM, Anthony Liguori wrote: > On 05/25/2010 08:31 AM, Avi Kivity wrote: >>> A protocol based mechanism has the advantage of being more robust in >>> the face of poorly written block backends so if it's possible to >>> make it perform as well as a plugin, it's a preferable approach. >> >> May be hard due to difficulty of exposing guest memory. > > If someone did a series to add plugins, I would expect a very strong > argument as to why a shared memory mechanism was not possible or at > least plausible. > > I'm not sure I understand why shared memory is such a bad thing wrt > KVM. Can you elaborate? Is it simply a matter of fork()? fork() doesn't work in the with of memory hotplug. What else is there? -- error compiling committee.c: too many arguments to function