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.
Regards,
Anthony Liguori
