From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:49072)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <peterx@redhat.com>) id 1eTLAO-000459-4K
	for qemu-devel@nongnu.org; Mon, 25 Dec 2017 00:19:13 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <peterx@redhat.com>) id 1eTLAK-0000Rp-VY
	for qemu-devel@nongnu.org; Mon, 25 Dec 2017 00:19:12 -0500
Received: from mx1.redhat.com ([209.132.183.28]:44536)
	by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)
	(Exim 4.71) (envelope-from <peterx@redhat.com>) id 1eTLAK-0000RI-Pf
	for qemu-devel@nongnu.org; Mon, 25 Dec 2017 00:19:08 -0500
Date: Mon, 25 Dec 2017 13:18:56 +0800
From: Peter Xu <peterx@redhat.com>
Message-ID: <20171225051856.GF2443@xz-mi>
References: <20171219084557.9801-1-peterx@redhat.com>
	<20171219084557.9801-19-peterx@redhat.com>
	<20171221114246.GO10812@lemon>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20171221114246.GO10812@lemon>
Subject: Re: [Qemu-devel] [RFC v6 18/27] monitor: send event when command
 queue full
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Fam Zheng <famz@redhat.com>
Cc: qemu-devel@nongnu.org, Stefan Hajnoczi <shajnocz@redhat.com>, "Daniel P . Berrange" <berrange@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Juan Quintela <quintela@redhat.com>, mdroth@linux.vnet.ibm.com, Eric Blake <eblake@redhat.com>, Laurent Vivier <lvivier@redhat.com>, Markus Armbruster <armbru@redhat.com>, marcandre.lureau@redhat.com, "Dr . David Alan Gilbert" <dgilbert@redhat.com>

On Thu, Dec 21, 2017 at 07:42:46PM +0800, Fam Zheng wrote:
> On Tue, 12/19 16:45, Peter Xu wrote:
> > Set maximum QMP command queue length to 8.  If queue full, instead of
> > queue the command, we directly return a "command-dropped" event, telling
> > client that specific command is dropped.
> > 
> > Note that this flow control mechanism is only valid if OOB is enabled.
> > If it's not, the effective queue length will always be 1, which strictly
> > follows original behavior of QMP command handling (which never drop
> > messages).
> > 
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> >  monitor.c | 17 ++++++++++++++++-
> >  1 file changed, 16 insertions(+), 1 deletion(-)
> > 
> > diff --git a/monitor.c b/monitor.c
> > index ed9a741d06..b571866659 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -4038,6 +4038,8 @@ static void monitor_qmp_bh_dispatcher(void *data)
> >      }
> >  }
> >  
> > +#define  QMP_REQ_QUEUE_LEN_MAX  (8)
> 
> Is this limit introspectable on QMP?

Not yet.  IMHO it's really QMP internal stuff, and I see no benefit so
far for a client to know about this...

-- 
Peter Xu