From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56250) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTWfc-0007PR-Uf for qemu-devel@nongnu.org; Wed, 10 Feb 2016 10:27:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aTWfU-0007zc-Dm for qemu-devel@nongnu.org; Wed, 10 Feb 2016 10:27:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46270) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aTWfU-0007zW-8h for qemu-devel@nongnu.org; Wed, 10 Feb 2016 10:27:00 -0500 References: <1454151394-52320-1-git-send-email-vsementsov@virtuozzo.com> <1454151394-52320-3-git-send-email-vsementsov@virtuozzo.com> <20160210100825.GA7317@stefanha-x1.localdomain> <56BB41AE.8090609@virtuozzo.com> From: John Snow Message-ID: <56BB56C2.40409@redhat.com> Date: Wed, 10 Feb 2016 10:26:58 -0500 MIME-Version: 1.0 In-Reply-To: <56BB41AE.8090609@virtuozzo.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/6] qmp: add query-block-dirty-bitmap-ranges List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Denis V. Lunev" , Stefan Hajnoczi , Vladimir Sementsov-Ogievskiy Cc: kwolf@redhat.com, famz@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com On 02/10/2016 08:57 AM, Denis V. Lunev wrote: > On 02/10/2016 01:08 PM, Stefan Hajnoczi wrote: >> On Sat, Jan 30, 2016 at 01:56:30PM +0300, Vladimir Sementsov-Ogievskiy >> wrote: >>> Add qmp command to query dirty bitmap contents. This is needed for >>> external backup. >>> >>> Signed-off-by: Vladimir Sementsov-Ogievskiy >>> --- >>> block/dirty-bitmap.c | 55 >>> +++++++++++++++++++++++++++++++++++++++ >>> blockdev.c | 62 >>> ++++++++++++++++++++++++++++++++++++++++++++ >>> include/block/dirty-bitmap.h | 7 +++++ >>> qapi/block-core.json | 54 >>> ++++++++++++++++++++++++++++++++++++++ >>> qmp-commands.hx | 33 +++++++++++++++++++++++ >>> 5 files changed, 211 insertions(+) >> This API produces large replies and/or requires many calls to fetch all >> bitmap data. The worst case is a 101010... bitmap. >> >> I consider the dirty bitmap to be data (vs control) and not something >> that should be sent over a control channel like the QMP monitor. >> >> How about writing the dirty bitmap to a file? The new bitmap file >> format that Fam is working on could be used. That way the dirty bitmap >> can be saved asynchronously without hogging the QMP monitor. > Reasonable point. > > May be it would be better to setup "special" NBD server inside > QEMU which will allow to directly "read" bitmap data. > > Any opinion? > > Den Or perhaps something like migration, where the client receiving the data opens a socket of some sort, and QEMU connects to that socket to send the data.