From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([140.186.70.92]:58544)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1QFmTr-0004rD-8W
	for qemu-devel@nongnu.org; Fri, 29 Apr 2011 08:07:32 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1QFmTq-0000k3-Ay
	for qemu-devel@nongnu.org; Fri, 29 Apr 2011 08:07:31 -0400
Received: from mx1.redhat.com ([209.132.183.28]:27985)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1QFmTq-0000jz-2B
	for qemu-devel@nongnu.org; Fri, 29 Apr 2011 08:07:30 -0400
Message-ID: <4DBAAA90.6010007@redhat.com>
Date: Fri, 29 Apr 2011 14:09:52 +0200
From: Kevin Wolf <kwolf@redhat.com>
MIME-Version: 1.0
References: <1303910855-28999-1-git-send-email-stefanha@linux.vnet.ibm.com>
	<1303910855-28999-3-git-send-email-stefanha@linux.vnet.ibm.com>
In-Reply-To: <1303910855-28999-3-git-send-email-stefanha@linux.vnet.ibm.com>
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH 2/8] qmp: Add QMP support for stream
	commands
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org, Adam Litke <agl@us.ibm.com>

Am 27.04.2011 15:27, schrieb Stefan Hajnoczi:
> From: Anthony Liguori <aliguori@us.ibm.com>
> 
> For leaf images with copy on read semantics, the stream commands allow the user
> to populate local blocks by manually streaming them from the backing image.
> Once all blocks have been streamed, the dependency on the original backing
> image can be removed.  Therefore, stream commands can be used to implement
> post-copy live block migration and rapid deployment.
> 
> The stream command can be used to stream a single sector, to start streaming
> the entire device, and to cancel an active stream.  It is easiest to allow the
> stream command to manage streaming for the entire device but a managent tool
> could use single sector mode to throttle the I/O rate.  When a single sector is
> streamed, the command returns an offset that can be used for a subsequent call.

You mean literally single sectors? You're not interested in completing
the job in finite time, are you? ;-)

I would suggest adding a length argument for the all=false case, so that
management tools can choose more reasonable sizes.

Kevin