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

[Kevin Wolf <kwolf@redhat.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