Luiz Capitulino <lcapitul...@redhat.com> wrote:
> On Wed, 26 May 2010 11:55:31 -0500
> Anthony Liguori <anth...@codemonkey.ws> 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.
