On Thu, Apr 07, 2022 at 05:16:45PM +0800, Han Han wrote:
> Hi developers,
> I have questions about balloon-change or control-error event:
> 1. What's the meaning of these events
> 2. When do the events occur?
>
> The comments of their callbacks don't mention that(
> https://gitlab.com/libvirt/libvirt/-/blob/master/include/libvirt/libvirt-domain.h#L4130
> https://gitlab.com/libvirt/libvirt/-/blob/master/include/libvirt/libvirt-domain.h#L3736
'balloon-change' is emitted any time the guest OS changes the ballon
inflation level.
eg if the host admin sets the balloon target to 1 GB and the guest is
currently using 2 GB, it might not be able to immediately drop down to
the 1 GB mark. The balloon-change events will emited as it make progress
towards teh 1 GB mark.
control-error is emitted when libvirt has some kind of problem controlling
the VM. The VM is still running, but libvirt may not be able to make changes
to its config. This can happen if libvirt has problems parsing JSON from QMP.
In practice it is highly unlikely for this to ever happen.
With regards,
Daniel
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