From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=33819 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OHfTL-00040x-5H for qemu-devel@nongnu.org; Thu, 27 May 2010 11:58:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OHfTF-0008LK-Ap for qemu-devel@nongnu.org; Thu, 27 May 2010 11:58:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47325) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OHfTF-0008L3-4K for qemu-devel@nongnu.org; Thu, 27 May 2010 11:58:09 -0400 From: Juan Quintela In-Reply-To: <20100527104845.341fa9e5@redhat.com> (Luiz Capitulino's message of "Thu, 27 May 2010 10:48:45 -0300") References: <9b6575587d22a5c85ec536172810520ee3b945d5.1274796992.git.quintela@redhat.com> <4BFBE843.5070202@codemonkey.ws> <4BFBF36D.8070208@codemonkey.ws> <20100525162549.GQ31759@redhat.com> <4BFBFBCB.2070806@codemonkey.ws> <20100526103346.GK18547@redhat.com> <4BFD361E.8070708@codemonkey.ws> <20100526151542.GU18547@redhat.com> <4BFD5283.70809@codemonkey.ws> <20100527104845.341fa9e5@redhat.com> Date: Thu, 27 May 2010 17:58:03 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: [Qemu-devel] Re: [PATCH 3/5] QMP: Introduce MIGRATION events List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino Cc: qemu-devel@nongnu.org Luiz Capitulino wrote: > On Wed, 26 May 2010 11:55:31 -0500 > Anthony Liguori wrote: >> That's exactly how the protocol is designed. That was one of the major >> improvements of QMP over the human monior. > > Yes and it already has 'id' support: > > { "execute": "cont", "id": "luiz" } > {"timestamp": {"seconds": 1274966635, "microseconds": 776813}, "event": "RESUME"} > {"return": {}, "id": "luiz"} > > But it doesn't detect duplicates, this is something I think it's up > to the client to do, do you agree? > >> This is how the info balloon command works, BTW. > > I won't remember the details now, but that interface has some issues and it > has to be reviewed. > >> Since there's a clear correlation between the request and the result of >> the request, an asynchronous command is what makes the most sense. It >> eliminates the problem of how to pass QErrors via an event which is one >> of the problems with the current event proposal. > > Not exactly, this is a problem with QError not the event proposal. We'll > have the same issue if we decide to include errno in the migrate errors and > the problem still exists with the BLOCK_IO_ERROR event. > > That said, I do agree that migrate should be asynchronous. This yet another > thing we may want to fix before 0.13. How difficult is that? > [...] > >> >> For tcp: and unix:, a CONNECTED event absolutely makes sense (every >> >> socket server should emit a CONNECTED event). Unfortunately, after >> >> CONNECTED you lose the monitor until migration is complete. If >> >> something bad happens, you have to exit qemu so once the monitor >> >> returns, migration has completed successfully. >> >> >> >> If we introduce live incoming migration, we'll need to rethink things. >> >> I would actually suggest that we deprecate the incoming command if we do >> >> that and make incoming migration a monitor command. I would think it >> >> should have the same semantics as migrate (as an asynchronous command). >> >> A CONNECTED event still makes sense for tcp and unix protocols but I >> >> don't think events make sense for start stop vs. an asynchronous command >> >> completion. >> >> >> > Do you actually mean 'deprecate -incoming arg' here ? >> > >> >> Yes. And by deprecate, I really mean that -incoming just becomes >> syntactic sugar for executing a monitor command immediately. > > But we can't change -incoming itself, since our command-line is supposed > to be stable, right? > > Also, Juan has said that replacing that arg with a monitor command > doesn't work, as qemu would have to be started in paused monitor for this > to work. > > So, what about introducing a -incoming-monitor command, which puts qemu > in the right state for migration, but requires a migrate_incoming command > to actually start migration? this -incoming-monitor is called -S, that should have a long name of -no-autostart that is what it does, and what we need for incoming migration as monitor command. Nothing new to see here. Later, Juan.