Re: [Qemu-devel] Re: [RFD] virtio: Add memory statistics reporting to the balloon driver

[Anthony Liguori]

On 01/07/2010 10:39 AM, Avi Kivity wrote:
> On 01/07/2010 06:27 PM, Adam Litke wrote:
> > > I think 'info-balloon' should be synchronous and without side-effects.
> > > ie return the current stats that QEMU has. We could then add a separate
> > > 'refresh-balloon' command + async event notification when that 
> > > completes.
> > > The tool that is requiring the stats could thus refresh as often as it
> > > likes.
> > This would work well for the QMP case, but what about for a traditional
> > monitor?  We could include a sequence number or timestamp in the memory
> > stats results so the user could tell that they were updated.  This
> > doesn't seem very user friendly though
>
> A user would have an easier time logging into the guest and using its 
> native tools.

Yeah, without objections, I like having info-balloon attempt to refresh 
stats, timeout after 10s, and return the last reported stats.  I think 
it also satisfies danpb's criteria of not wasting cpu cycles polling.

Regards,

Anthony Liguori