On Thu, Oct 15, 2015 at 03:06:19PM +0200, Alberto Garcia wrote: > On Tue 13 Oct 2015 05:38:30 PM CEST, Stefan Hajnoczi wrote: > > >> query-blockstats always returns a BlockDeviceStats structure for each > >> BDS, regardless of whether it implements accounting or not. Since the > >> field is mandatory there's no way to tell that from the values alone. > >> > >> This field solves that problem by indicating which BDSs support I/O > >> accounting. > > > > I'm not sure I understand the problem. > > > > If I/O accounting isn't being used then all fields will be 0? > > Yes, but there's no way to tell if that happens because I/O accounting > is not supported or because there hasn't been any I/O yet. > > There's one additional problem: this patch assumes that accounting is > supported if this BDS is attached to a BlockBackend. But we don't know > if the device model supports accounting or not, I still need to figure > out what's the best way to do it.
Is there a corresponding libvirt patch or why does it matter whether the QMP client can detect whether blockstats are available? Stefan
