After setting a balloon target value, applications have to
continually poll 'query-balloon' to determine whether the
guest has reacted to this request. The virtio-balloon backend
knows exactly when the guest has reacted though, and thus it
is possible to emit a JSON event to tell the mgmt application
whenever the guest balloon changes.
This introduces a new 'qemu_balloon_changed()' API which is
to be called by balloon driver backends, whenever they have
a change in balloon value. This takes the 'actual' balloon
value, as would be found in the BalloonInfo struct.
The qemu_balloon_change API emits a JSON monitor event which
looks like:
{"timestamp": {"seconds":
1337162462, "microseconds": 814521},
"event": "BALLOON_CHANGE", "data": {"actual":
944766976}}
* balloon.c, balloon.h: Introduce qemu_balloon_changed() for
emitting balloon change events on the monitor
* hw/virtio-balloon.c: Invoke qemu_balloon_changed() whenever
the guest changes the balloon actual value
* monitor.c, monitor.h: Define QEVENT_BALLOON_CHANGE
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
"len": 10737418240, "offset": 134217728,
"speed": 0 },
"timestamp": { "seconds": 1267061043, "microseconds": 959568 } }
+
+
+BALLOON_CHANGE
+----------
+
+Emitted when the guest changes the actual BALLOON level. This
+value is equivalent to the 'actual' field return by the
+'query-balloon' command
+
+Data:
+
+- "actual": actual level of the guest memory balloon in bytes (json-number)
+
+Example:
+
+{ "event": "BALLOON_CHANGE",
+ "data": { "actual": 944766976 },
+ "timestamp": { "seconds": 1267020223, "microseconds": 435656 } }
#include "balloon.h"
#include "trace.h"
#include "qmp-commands.h"
+#include "qjson.h"
static QEMUBalloonEvent *balloon_event_fn;
static QEMUBalloonStatus *balloon_stat_fn;
return 1;
}
+void qemu_balloon_changed(int64_t actual)
+{
+ QObject *data;
+
+ data = qobject_from_jsonf("{ 'actual': %" PRId64 " }",
+ actual);
+
+ monitor_protocol_event(QEVENT_BALLOON_CHANGE, data);
+
+ qobject_decref(data);
+}
+
+
BalloonInfo *qmp_query_balloon(Error **errp)
{
BalloonInfo *info;
QEMUBalloonStatus *stat_func, void *opaque);
void qemu_remove_balloon_handler(void *opaque);
+void qemu_balloon_changed(int64_t actual);
+
#endif
{
VirtIOBalloon *dev = to_virtio_balloon(vdev);
struct virtio_balloon_config config;
+ uint32_t oldactual = dev->actual;
memcpy(&config, config_data, 8);
dev->actual = le32_to_cpu(config.actual);
+ if (dev->actual != oldactual) {
+ qemu_balloon_changed(ram_size -
+ (dev->actual << VIRTIO_BALLOON_PFN_SHIFT));
+ }
}
static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
[QEVENT_DEVICE_TRAY_MOVED] = "DEVICE_TRAY_MOVED",
[QEVENT_SUSPEND] = "SUSPEND",
[QEVENT_WAKEUP] = "WAKEUP",
+ [QEVENT_BALLOON_CHANGE] = "BALLOON_CHANGE",
};
QEMU_BUILD_BUG_ON(ARRAY_SIZE(monitor_event_names) != QEVENT_MAX)
QEVENT_DEVICE_TRAY_MOVED,
QEVENT_SUSPEND,
QEVENT_WAKEUP,
+ QEVENT_BALLOON_CHANGE,
/* Add to 'monitor_event_names' array in monitor.c when
* defining new events here */