On Fri, Feb 17, 2012 at 10:55:41AM -0600, Anthony Liguori wrote: > On 02/08/2012 02:30 PM, Luiz Capitulino wrote: > >This commit adds a QMP API for the guest provided memory statistics > >(long disabled by commit 07b0403dfc2b2ac179ae5b48105096cc2d03375a). > > > >The approach taken by the original commit > >(625a5befc2e3200b396594f002218d235e375da5) was to extend the > >query-balloon command. It introduced a severe bug though: query-balloon > >would hang if the guest didn't respond. > > > >The approach taken by this commit is asynchronous and thus avoids > >any QMP hangs. > > > >First, a client has to issue the balloon-get-memory-stats command. > >That command gets the process started by only sending a request to > >the guest, it doesn't block. When the memory stats are made available > >by the guest, they are returned to the client as an QMP event. > > > >Signed-off-by: Luiz Capitulino<lcapitul...@redhat.com> > > Do we need this to be stable in 1.1? > > We can do this pretty nicely through QOM. We can have a polling > property in the virtio-balloon driver, that when set, will enable > the virtio-balloon device to poll the guest for statistics. > > We can also have properties for each of the memory statistics and a > timestamp for when the last update was. > > I think this is a friendlier approach for clients, and a cleaner > approach from a QEMU perspective. > > There's nothing generic about this functionality. It's extremely > specific to virtio-balloon. We just lacked ways to expose device > specific function pre-QOM.
I'm not so sure, I think proxying guest agent commands through QMP would hit very similar snags, for instance. > > Regards, > > Anthony Liguori > >
