From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=44051 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Ooc1r-0007ot-FD for qemu-devel@nongnu.org; Thu, 26 Aug 2010 08:58:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1Ooc1q-0006GK-9N for qemu-devel@nongnu.org; Thu, 26 Aug 2010 08:58:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:61831) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1Ooc1q-0006G7-30 for qemu-devel@nongnu.org; Thu, 26 Aug 2010 08:58:02 -0400 Date: Thu, 26 Aug 2010 09:57:48 -0300 From: Luiz Capitulino Subject: Re: [Qemu-devel] [PATCH V2] balloon: Don't try fetching info if machine is stopped Message-ID: <20100826095748.7e0b12ad@doriath> In-Reply-To: <20100826082842.GE9564@redhat.com> References: <8450ea8e785c9049f0b3edddc01650a8c4b9ffe7.1282265244.git.amit.shah@redhat.com> <4C719C7E.6030606@codemonkey.ws> <20100826060513.GF18351@amit-laptop.redhat.com> <4C762058.8070301@redhat.com> <20100826081750.GK18351@amit-laptop.redhat.com> <20100826082842.GE9564@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: Amit Shah , Paolo Bonzini , agl@us.ibm.com, qemu list , Juan Quintela On Thu, 26 Aug 2010 09:28:42 +0100 "Daniel P. Berrange" wrote: > On Thu, Aug 26, 2010 at 01:47:50PM +0530, Amit Shah wrote: > > On (Thu) Aug 26 2010 [10:05:44], Paolo Bonzini wrote: > > > On 08/26/2010 08:05 AM, Amit Shah wrote: > > > >This is what I have currently. It would need some timer handling in > > > >the save/load case as well, right? > > > > > > When loading you won't have any pending "info balloon" command, so I > > > think the timer need not be preserved across migration. > > > > > > Also, 5 seconds for a stopped guest is actually a lot, > > > > That's the problem; it's policy. Where and how to specify it? > > It is unfortunate that this is policy, but we just have to accept > that the current query-balloon command is a flawed design. IMHO > we should just hardcode the timeout at 5 seconds as you do (plus > immediate return for paused guests). Then focus on adding new > monitor commands/events to deal with balloon query in a way > that doesn't require this kind of policy in QEMU, and deprecate > the existing query-balloon command. Agreed, but it's not just that: we've never correctly specified how commands that talk with the guest should behave. *brain dump warning* We were talking about making all commands work as synchronous and asynchronous. If we do that, then we'll need a 'global' timeout for all synchronous commands. We could have a default value and a command to set it. *brain dump warning ends* I really don't know what to do 0.13. Probably the hard-coded timer is the best solution we have, but I'm wondering if it's going to cause problems in the near future, when we get proper asynchronous command support.