From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LrubA-0002F4-S6 for qemu-devel@nongnu.org; Thu, 09 Apr 2009 09:47:20 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Lrub6-0002CU-RC for qemu-devel@nongnu.org; Thu, 09 Apr 2009 09:47:20 -0400 Received: from [199.232.76.173] (port=32896 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Lrub6-0002CI-LT for qemu-devel@nongnu.org; Thu, 09 Apr 2009 09:47:16 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:33406) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1Lrub6-0001sT-2V for qemu-devel@nongnu.org; Thu, 09 Apr 2009 09:47:16 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e32.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n39DiI0P003123 for ; Thu, 9 Apr 2009 07:44:18 -0600 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n39DlAl3209216 for ; Thu, 9 Apr 2009 07:47:11 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n39DlAf2016152 for ; Thu, 9 Apr 2009 07:47:10 -0600 Message-ID: <49DDFC5C.4080504@us.ibm.com> Date: Thu, 09 Apr 2009 08:47:08 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH 1/6] Allow multiple monitor devices (v2) References: <1239215702-23818-1-git-send-email-aliguori@us.ibm.com> <49DDAF9F.7040400@redhat.com> <49DDF807.1050707@us.ibm.com> <49DDFAD5.7060808@redhat.com> In-Reply-To: <49DDFAD5.7060808@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: libvir-list@redhat.com, Jan Kiszka , qemu-devel@nongnu.org, Hollis Blanchard Avi Kivity wrote: > hotplug disk > -ENOSPC on disk > > It's true that events don't correlate directly to commands, but they > do correlate to the state of the system and that is affected by commands. events are time stamped. In non-human mode, I think command responses should be time stamped too so that a management tool knows when the event was generated and can correlate the system state to the particular event. >>> Sure, we'll need to make sure notifications don't mix with command >>> responses, and that all commands are acked (the (qemu) prompt serves >>> that purpose now), but it seems to me do be a lot easier for the >>> management end. >> >> FWIW, you can have asynchronous completion of monitor commands. See >> migration as an example. The (qemu) prompt is the ack that the >> command is finished. You can only have one async command per monitor >> session which is why you need multiple monitors. > > Migration has the -d switch to be truly async (not to wait). We need > an async notifier to tell us migration has finished or failed. Multiplexing multiple monitor sessions AFAICT is going to require a non-human mode. But it's totally orthogonal to this patch set. You could implement it today if you wanted. >> >> If we had a non-human monitor mode, I think it would be fine to have >> many monitors multiplexed over a single channel. The internal >> monitor abstraction doesn't change. > > I don't understand why we need to multiplex many monitors over one > channel. Let's keep one monitor, but with the ability to send > notifications to the other end. I don't understand how you think it would be implemented. Each command is going to have a unique 'Monitor *' associated with it. How that ends up being displayed to the user/management tool is irrelevant. Right now, you can only have one 'Monitor *' active on a single "channel" at a time. This is mostly a matter of output format. I don't see how we can keep the monitor output consistent and compatible as it stands today and still support multiple 'Monitor *'s active in a single channel. -- Regards, Anthony Liguori