balloon: re-enable balloon stats
The statistics are now available through device properties via a
polling mechanism. First a client has to enable polling, then it
can query available stats.
Polling is enabled by setting an update interval (in seconds)
to a property named guest-stats-polling-interval, like this:
{ "execute": "qom-set",
"arguments": { "path": "/machine/peripheral-anon/device[1]",
"property": "guest-stats-polling-interval", "value": 4 } }
Then the available stats can be retrieved by querying the
guest-stats property. The returned object is a dict containing
all available stats. Example:
{ "execute": "qom-get",
"arguments": { "path": "/machine/peripheral-anon/device[1]",
"property": "guest-stats" } }
{
"return": {
"stats": {
"stat-swap-out": 0,
"stat-free-memory":
844943360,
"stat-minor-faults": 219028,
"stat-major-faults": 235,
"stat-total-memory":
1044406272,
"stat-swap-in": 0
},
"last-update":
1358529861
}
}
Please, check the next commit for full documentation.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>