From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:53275) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RyR85-0005nS-7U for qemu-devel@nongnu.org; Fri, 17 Feb 2012 11:57:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RyR7v-00040G-F3 for qemu-devel@nongnu.org; Fri, 17 Feb 2012 11:57:53 -0500 Received: from e1.ny.us.ibm.com ([32.97.182.141]:58125) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RyR7v-000402-CU for qemu-devel@nongnu.org; Fri, 17 Feb 2012 11:57:43 -0500 Received: from /spool/local by e1.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 17 Feb 2012 11:57:40 -0500 Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id 137716E8057 for ; Fri, 17 Feb 2012 11:55:43 -0500 (EST) Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q1HGtgxF213210 for ; Fri, 17 Feb 2012 11:55:42 -0500 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q1HGtgaB031982 for ; Fri, 17 Feb 2012 11:55:42 -0500 Message-ID: <4F3E868D.8020107@us.ibm.com> Date: Fri, 17 Feb 2012 10:55:41 -0600 From: Anthony Liguori MIME-Version: 1.0 References: <1328733040-16697-1-git-send-email-lcapitulino@redhat.com> <1328733040-16697-7-git-send-email-lcapitulino@redhat.com> In-Reply-To: <1328733040-16697-7-git-send-email-lcapitulino@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 6/6] qmp: add balloon-get-memory-stats & event List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino Cc: agl@us.ibm.com, eblake@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com 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 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