Re: [Qemu-devel] [PATCH 2/8] qmp: Add QMP support for stream commands

[Stefan Hajnoczi <stefanha@gmail.com>]

On Fri, Apr 29, 2011 at 1:09 PM, Kevin Wolf <kwolf@redhat.com> wrote:
> 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.

Discussion on libvir-list suggests the same thing.  Let's take a
nb_sectors where 0=all.

Stefan