Re: [Qemu-devel] [PATCH 0/4] Image Streaming API

[Adam Litke <agl@us.ibm.com>]

On Tue, Aug 30, 2011 at 10:28:09AM +0100, Stefan Hajnoczi wrote:
> On Tue, Aug 30, 2011 at 4:19 AM, Zhi Yong Wu <zwu.kernel@gmail.com> wrote:
> > On Tue, Aug 23, 2011 at 8:58 PM, Stefan Hajnoczi
> > <stefanha@linux.vnet.ibm.com> wrote:
> >> These patches put in place the image streaming QMP/HMP commands and
> >> documentation.  Image streaming itself is not implemented by this patch series
> >> but the HMP/QMP commands that libvirt uses are implemented to return
> >> NotSupported.
> >>
> >> The Image Streaming API can be used to copy the contents of a backing file into
> >> the image file while the guest is running.  The API is described on the wiki:
> >> http://wiki.qemu.org/Features/LiveBlockMigration/ImageStreamingAPI
> >
> > If query-block-jobs returns one percent value, it will be more
> > readable and convenient for users.
> 
> QMP is not a human interface.  Although a percentage value is good for
> progress bars, the absolute value is also interesting in terms of how
> much work is being done.  By providing an end value and a current
> value the management tool can display either or both.

I agree.  In QMP, we should report the best, most granular information we have
and allow management tools to present it as they see fit.  For example, a
management tool may wish to present streaming progress as a spinner (rather than
a progress bar).  In that case you would want to see the numbers updated
whenever progress has been made.