From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53498) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfBrx-000471-B5 for qemu-devel@nongnu.org; Thu, 14 Jun 2012 11:22:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SfBro-00038S-Q5 for qemu-devel@nongnu.org; Thu, 14 Jun 2012 11:21:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:21737) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfBro-000389-I3 for qemu-devel@nongnu.org; Thu, 14 Jun 2012 11:21:48 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q5EFLk2t004091 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 14 Jun 2012 11:21:47 -0400 Message-ID: <4FDA0188.4080705@redhat.com> Date: Thu, 14 Jun 2012 17:21:44 +0200 From: Pavel Hrdina MIME-Version: 1.0 References: <806c66b2f071f03bec0b7d45a71512e394386885.1339617170.git.phrdina@redhat.com> <4FD9D67F.5080505@redhat.com> <4FD9FB83.8050208@redhat.com> <4FD9FD6A.2080702@redhat.com> In-Reply-To: <4FD9FD6A.2080702@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2] qapi: converted commit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: kwolf@redhat.com, Jeff Cody , qemu-devel@nongnu.org, lcapitulino@redhat.com On 06/14/2012 05:04 PM, Eric Blake wrote: > On 06/14/2012 08:56 AM, Pavel Hrdina wrote: >> On 06/14/2012 02:18 PM, Eric Blake wrote: >>> On 06/14/2012 01:35 AM, Pavel Hrdina wrote: >>>> Signed-off-by: Pavel Hrdina >>>> --- >>>> +++ b/qapi-schema.json >>>> @@ -1169,6 +1169,21 @@ >>>> { 'command': 'block_resize', 'data': { 'device': 'str', 'size': >>>> 'int' }} >>>> >>>> ## >>>> +# @commit >>>> +# >>>> +# Commit changes to the disk images (if -snapshot is used) or >>>> backing files. >>>> +# >>>> +# @device: the name of the device or the "all" to commit all devices >>>> +# >>>> +# Returns: nothing on success >>>> +# If @device is not a valid block device, DeviceNotFound >>>> +# If a long-running operation is using the device, DeviceInUse >>>> +# >>>> +# Since: 1.2 >>>> +## >>>> +{ 'command': 'commit', 'data': { 'device': 'str' }} >>> Should we use this as an opportunity to make the command more powerful? >>> For example, integrating this with the 'transaction' command or a block >>> job queried by 'query-block-jobs' to track its progress would be useful. >>> Also, suppose I have A<- B<- C. Does 'commit' only do one layer (C >>> into B), or all layers (B and C into A)? That argues that we need an >>> optional parameter that says how deep to commit (committing C into B >>> only to repeat and commit B into A is more time-consuming than directly >>> committing both B and C into A to start with). When a commit is >>> complete, which file is backing the device - is it still C (which >>> continues to diverge, but now from the point of the commit) or does qemu >>> pivot things to have the device now backed by B (and C can be discarded, >>> particularly true if changes are now going into B which invalidate C). >> What i find out is that 'commit' will commit changes only from C to B >> and qemu continues with C from the new commit point. I couldn't find a >> way to commit changes and go back to backing file. This should be >> supported by parameter and also as you mention that commit all changes >> through all snapshots should be supported by another parameter. >> The 'transaction' feature would be nice to have too. > Which makes it sound like we're starting to overlap with Jeff's work on > 'block-commit'. > > If 'block-commit' proves to be better all around at doing what we want, > do we even need to keep 'commit' in QMP, or would it be okay for HMP only? If the 'block-commit' will be better I think that we could drop the 'commit' completely. And have only 'block-commit' for both QMP and HMP. Pavel