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From: Paolo Bonzini <pbonzini@redhat.com>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: kwolf@redhat.com, Jeff Cody <jcody@redhat.com>,
	mtosatti@redhat.com, armbru@redhat.com, qemu-devel@nongnu.org,
	Federico Simoncelli <fsimonce@redhat.com>,
	Luiz Capitulino <lcapitulino@redhat.com>
Subject: Re: [Qemu-devel] drive transactions (was Re: [PATCH 2/2 v2] Add the blockdev-reopen and blockdev-migrate commands)
Date: Mon, 27 Feb 2012 15:54:41 +0100	[thread overview]
Message-ID: <4F4B9931.30708@redhat.com> (raw)
In-Reply-To: <4F4B9761.3010601@codemonkey.ws>

On 02/27/2012 03:46 PM, Anthony Liguori wrote:
> I think a better way to think of this is as a batch submission.  It
> would be relatively easy to model in QMP too (just have a batch-command
> that has a list of commands as it's argument).
> 
> The difference between batch submission and a transaction is atomic
> rollback. But I don't think atomic rollback is really needed here.

A transaction enforces atomicity at the block layer level.  It's
different from batch commands in two ways:

* bdrv_drain_all/bdrv_flush needs to be called at the beginning of the
commit.  This may not be the case with batch commands.

* with batch commands, atomicity happens by chance because VCPUs cannot
send I/O while the monitor is holding the global mutex.

Paolo

  reply	other threads:[~2012-02-27 14:54 UTC|newest]

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-22 17:13 [Qemu-devel] Live Block Migration using Mirroring Federico Simoncelli
2012-02-22 17:13 ` [Qemu-devel] [PATCH 1/3] Add blkmirror block driver Federico Simoncelli
2012-02-23 16:14   ` Stefan Hajnoczi
2012-02-23 16:18     ` Stefan Hajnoczi
2012-02-23 16:20       ` Federico Simoncelli
2012-02-23 16:28         ` Stefan Hajnoczi
2012-02-23 16:51           ` Federico Simoncelli
2012-02-23 16:18     ` Federico Simoncelli
2012-02-27  9:23     ` Stefan Hajnoczi
2012-02-27 11:37       ` Paolo Bonzini
2012-02-27 11:42         ` Stefan Hajnoczi
2012-02-27 11:48           ` Paolo Bonzini
2012-02-27 13:09             ` Stefan Hajnoczi
2012-02-27 13:47               ` Paolo Bonzini
2012-02-27 14:49                 ` Stefan Hajnoczi
2012-02-27 14:59                   ` Stefan Hajnoczi
2012-02-27 15:08                     ` Paolo Bonzini
2012-02-22 17:13 ` [Qemu-devel] [PATCH 2/3] Update the " Federico Simoncelli
2012-02-23  7:18   ` Paolo Bonzini
2012-02-23  9:44     ` Federico Simoncelli
2012-02-23  9:45       ` Paolo Bonzini
2012-02-22 17:13 ` [Qemu-devel] [PATCH 3/3] Add nocreate option to snapshot_blkdev Federico Simoncelli
2012-02-23  7:19   ` Paolo Bonzini
2012-02-23  7:38     ` Paolo Bonzini
2012-02-23  9:39       ` Federico Simoncelli
2012-02-23  9:48         ` Paolo Bonzini
2012-02-23 10:19           ` Federico Simoncelli
2012-02-23 11:30             ` Paolo Bonzini
2012-02-23 15:47 ` [Qemu-devel] Live Block Migration using Mirroring Stefan Hajnoczi
2012-02-23 16:10   ` Federico Simoncelli
2012-02-23 16:35 ` Stefan Hajnoczi
2012-02-23 17:06   ` Federico Simoncelli
2012-02-24 11:37 ` [Qemu-devel] [PATCH 1/2] Add blkmirror block driver Federico Simoncelli
2012-02-24 11:37 ` [Qemu-devel] [PATCH 2/2] Add the blockdev-reopen and blockdev-migrate commands Federico Simoncelli
2012-02-24 12:03   ` Kevin Wolf
2012-02-24 12:12     ` Federico Simoncelli
2012-02-24 13:11     ` Paolo Bonzini
2012-02-24 17:04     ` Luiz Capitulino
2012-02-27 14:57     ` Markus Armbruster
2012-02-24 16:49 ` [Qemu-devel] [PATCH 1/2 v2] Add blkmirror block driver Federico Simoncelli
2012-02-24 17:02   ` Eric Blake
2012-02-24 17:15     ` Federico Simoncelli
2012-02-24 18:49     ` Paolo Bonzini
2012-02-24 18:17   ` Luiz Capitulino
2012-02-27  9:17     ` Federico Simoncelli
2012-02-24 16:49 ` [Qemu-devel] [PATCH 2/2 v2] Add the blockdev-reopen and blockdev-migrate commands Federico Simoncelli
2012-02-24 17:46   ` Eric Blake
2012-02-24 18:57     ` Paolo Bonzini
2012-02-24 19:37       ` Eric Blake
2012-02-24 19:01   ` Luiz Capitulino
2012-02-24 19:40     ` Eric Blake
2012-02-24 20:26       ` Luiz Capitulino
2012-02-24 22:46         ` Eric Blake
2012-02-24 20:32     ` Paolo Bonzini
2012-02-24 20:36       ` Luiz Capitulino
2012-02-24 21:05         ` Paolo Bonzini
2012-02-24 22:30     ` Eric Blake
2012-02-25  6:47       ` Paolo Bonzini
2012-02-27 11:29     ` Federico Simoncelli
2012-02-27 12:12       ` Luiz Capitulino
2012-02-27 12:49         ` Paolo Bonzini
2012-02-27 13:06           ` Luiz Capitulino
2012-02-27 14:39             ` [Qemu-devel] drive transactions (was Re: [PATCH 2/2 v2] Add the blockdev-reopen and blockdev-migrate commands) Paolo Bonzini
2012-02-27 14:46               ` Anthony Liguori
2012-02-27 14:54                 ` Paolo Bonzini [this message]
2012-02-27 14:59                   ` Anthony Liguori
2012-02-27 15:03                     ` Paolo Bonzini
2012-02-27 15:06                       ` Anthony Liguori
2012-02-27 15:17                     ` Kevin Wolf
2012-02-27 15:24                       ` Anthony Liguori
2012-02-27 16:51                         ` Paolo Bonzini
2012-02-27 16:58                           ` Anthony Liguori
2012-02-27 17:06                             ` Paolo Bonzini
2012-02-27 16:33               ` Federico Simoncelli
2012-02-27 16:41                 ` Paolo Bonzini
2012-02-27 16:42                 ` Anthony Liguori
2012-02-27 16:50                   ` Federico Simoncelli
2012-02-27 16:53                     ` Anthony Liguori
2012-02-27 16:54                       ` Paolo Bonzini
2012-02-27 16:59                         ` Anthony Liguori
2012-02-27 17:37                   ` Luiz Capitulino
2012-02-28 15:47 ` [Qemu-devel] Live Block Migration using Mirroring Stefan Hajnoczi
2012-02-28 17:15   ` Federico Simoncelli
2012-02-28 17:36     ` Paolo Bonzini
2012-02-28 17:46       ` Federico Simoncelli
2012-02-28 18:02         ` Paolo Bonzini
2012-02-28 18:21           ` Federico Simoncelli
2012-02-28 17:26   ` Paolo Bonzini
2012-02-29 12:28   ` [Qemu-devel] [PATCHv3] Add blkmirror block driver Federico Simoncelli
2012-02-29 13:02     ` Federico Simoncelli
2012-02-29 17:01   ` [Qemu-devel] [PATCHv4] " Federico Simoncelli
2012-03-05 16:59 ` [Qemu-devel] Live Block Migration using Mirroring Marcelo Tosatti
2012-03-05 17:20   ` Eric Blake
2012-03-05 17:44     ` Marcelo Tosatti
2012-03-05 18:05       ` Paolo Bonzini

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