Re: [Qemu-devel] [PATCH 1/3] balloon: drop old stats code & API

[Dietmar Maurer]

> Libvirt has been using it when available (although reluctantly, as it risks
> hanging on an uncooperative guest); and while libvirt can be patched to call 6
> QOM commands in a row to query six different QOM stats, I still think it
> would be nicer to add a command that provides all the stats at once.  In
> particular, when calling 6 commands in series, you no longer have an atomic
> picture of the guest (the polling interval could hit between two QOM queries,
> resulting in a combined set of statistics that has no counterpart to the
> transition of states that the guest actually went through).  On the other 
> hand,
> since the stats are already polling-based, and since it requires cooperation
> from the guest, not having a guarantee of an atomic set of stats is not really
> much of a loss.

I already implemented that and sent patches to this list. The patch is more or 
less
trivial -  we simply read the cached values. It does not hang on an 
uncooperative guest, and works without any problems.

But unfortunately, Luiz dislikes the patch (I do not understand why). So I 
stopped posting it.