On Mon, 23 Apr 2012 11:33:27 -0600
Eric Blake<address@hidden> wrote:
On 04/23/2012 09:39 AM, Stefan Hajnoczi wrote:
This series is based on Luiz' latest QMP pull request at
git://repo.or.cz/qemu/qmp-unstable.git queue/qmp
(d980956d5bfa9f4fd56c00a0b168c3c0f67bc0d2). This dependency is necessary
because this series conflicts with the block_stream -> block-stream rename.
Eric Blake raised concerns about the inability to start block jobs with a speed
limit. Current the user needs to follow up the block-stream command with
block-job-set-speed. There is a window of time while the new block job is
running but block-job-set-speed has not been processed yet.
This series adds an optional 'speed' parameter to block-stream so streaming can
be started with a speed limit that takes effect immediately.
I considered several other approaches, including adding a
default_block_job_speed field to BlockDriverState but ultimately the cleanest
solution is to pass in a speed parameter on job creation. This way we do not
change semantics of existing commands, we only add an optional parameter. We
also do not need to add state to BlockDriverState, which is already huge and
messy.
I like the approach of adding a new optional parameter; that is a
workable solution for libvirt (that is, libvirt can assume that if the
spelling 'block-stream' is available, then so is the optional 'speed'
parameter, if this patch is included in time for qemu 1.1).
The optional parameter is fine for me too, but we recently had a
discussion where it was decided that we should add new commands instead
of extending existing ones.
Anthony, I believe we're already taking that position, right?