From 973603a813c5d60534b4fa0313f83be40e2b9c47 Mon Sep 17 00:00:00 2001 From: "Daniel P. Berrange" Date: Thu, 14 Jun 2012 18:12:56 +0100 Subject: Add event notification for guest balloon changes 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 Acked-by: Amit Shah Signed-off-by: Luiz Capitulino --- QMP/qmp-events.txt | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'QMP') diff --git a/QMP/qmp-events.txt b/QMP/qmp-events.txt index 9286af569d..9ba7079589 100644 --- a/QMP/qmp-events.txt +++ b/QMP/qmp-events.txt @@ -335,3 +335,21 @@ Example: "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 } } -- cgit v1.2.3