On Wed 03 Jun 2015 04:18:45 PM CEST, Eric Blake wrote: >> The accounting stats are stored in the BlockDriverState, but they're >> actually from the device backed by the BDS, so they could probably be >> moved there. For the interface we could extend BlockDeviceStats and >> add the new fields, but query-blockstats works on BDS, so maybe we >> need new API? > > We want stats per BDS (it would be nice to know how many reads are > satisfied from the active layer, vs. how many are satisfied from the > backing image, to know how stable and useful the backing image is). > But we also want stats per BB (how many reads did the guest attempt, > regardless of which BDS served the read). So any good solution needs > to work from both views (whether by two API, or by one with a flag, is > bike-shedding).
That's right. As I said my priority is the stats from the BB (i.e. what the guest can see), but I agree that any solution has to consider that we want to have both eventually. Berto
