From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59412) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TiUbX-0006kS-IX for qemu-devel@nongnu.org; Tue, 11 Dec 2012 13:30:56 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TiUbR-0005I7-NB for qemu-devel@nongnu.org; Tue, 11 Dec 2012 13:30:55 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58032) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TiUbR-0005I3-Bk for qemu-devel@nongnu.org; Tue, 11 Dec 2012 13:30:49 -0500 Date: Tue, 11 Dec 2012 16:30:30 -0200 From: Luiz Capitulino Message-ID: <20121211163030.0647caae@doriath.home> In-Reply-To: <20121211162840.4b01701e@doriath.home> References: <1355168173-14571-1-git-send-email-lcapitulino@redhat.com> <24E144B8C0207547AD09C467A8259F7557870AEE@lisa.maurer-it.com> <20121211094513.29fa32bd@doriath.home> <24E144B8C0207547AD09C467A8259F755787AC78@lisa.maurer-it.com> <20121211105947.1b92f411@doriath.home> <24E144B8C0207547AD09C467A8259F755787E011@lisa.maurer-it.com> <20121211173808.GH30686@vm> <20121211162840.4b01701e@doriath.home> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/3] re-enable balloon stats List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: mdroth Cc: "qemu-devel@nongnu.org" , "aliguori@us.ibm.com" , Dietmar Maurer , "agl@us.ibm.com" On Tue, 11 Dec 2012 16:28:40 -0200 Luiz Capitulino wrote: > On Tue, 11 Dec 2012 11:38:08 -0600 > mdroth wrote: > > > On Tue, Dec 11, 2012 at 03:14:02PM +0000, Dietmar Maurer wrote: > > > > > > I'm not sure I like this for two reasons. First, there will be cases > > > > > > where the user doesn't want this to be enabled. Second, we'll be > > > > > > forcing an interval on users. > > > > > > > > > > So when should we set the stats-polling-interval? I first thought I > > > > > simply set that at VM start, but that triggers an error: > > > > > > > > > > "guest doesn't support balloon stats" > > > > > > > > > > because the balloon driver is not loaded. > > > > > > > > Yes, it's required to have the balloon driver loaded. The stats are reported by > > > > it. > > > > > > That does not really answers my question. So you think the management > > > framework should start the VM, and then wait until the balloon driver is > > > loaded? That sound very clumsy to me. > > > > > > I mean, I just want to set the polling interval. Why does that need the balloon drive loaded > > > inside the guest (polling is done by the host)? > > > > I agree. Should lack of a balloon module disable the timer > > completely, or just silently fail? Management can always reference > > stats-last-update to check that stats are being reported properly. -1 would > > mean driver was never loaded, longer update intervals might mean guest > > was rebooted/suspended/etc, but in both cases it makes sense that the > > timer still try to fetch stats, and the determination of what stats are > > valid/invalid be left to management. > > I could move the check for the stats feature bit from the function that > enables polling to the timer callback. This would solve Dietmar's use-case, > but it would silently fail if the feature is never negotiated (as you said > above). Btw, we could also add functionality to qemu-ga to list loaded modules.