From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:43441)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <yuanhan.liu@linux.intel.com>) id 1ZWkT8-0007DI-LJ
	for qemu-devel@nongnu.org; Tue, 01 Sep 2015 08:15:24 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <yuanhan.liu@linux.intel.com>) id 1ZWkT4-0004AR-H8
	for qemu-devel@nongnu.org; Tue, 01 Sep 2015 08:15:18 -0400
Received: from mga14.intel.com ([192.55.52.115]:12701)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <yuanhan.liu@linux.intel.com>) id 1ZWkT4-00049D-C3
	for qemu-devel@nongnu.org; Tue, 01 Sep 2015 08:15:14 -0400
Date: Tue, 1 Sep 2015 20:16:44 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Message-ID: <20150901121644.GF3054@yliu-dev.sh.intel.com>
References: <1439360742-2186-2-git-send-email-changchun.ouyang@intel.com>
	<20150813121013-mutt-send-email-mst@redhat.com>
	<F52918179C57134FAEC9EA62FA2F962511CDB3AF@shsmsx102.ccr.corp.intel.com>
	<20150827154430-mutt-send-email-mst@redhat.com>
	<F52918179C57134FAEC9EA62FA2F962511CE786D@shsmsx102.ccr.corp.intel.com>
	<20150830091225-mutt-send-email-mst@redhat.com>
	<F52918179C57134FAEC9EA62FA2F962511CECCC2@shsmsx102.ccr.corp.intel.com>
	<20150831142809-mutt-send-email-mst@redhat.com>
	<20150901092006.GC3054@yliu-dev.sh.intel.com>
	<20150901124105-mutt-send-email-mst@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20150901124105-mutt-send-email-mst@redhat.com>
Subject: Re: [Qemu-devel] [snabb-devel] Re: [PATCH v6 1/2] vhost-user: add
 multi queue support
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: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "snabb-devel@googlegroups.com" <snabb-devel@googlegroups.com>, "thibaut.collet@6wind.com" <thibaut.collet@6wind.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "n.nikolaev@virtualopensystems.com" <n.nikolaev@virtualopensystems.com>, "luke@snabb.co" <luke@snabb.co>, "Long,
	Thomas" <thomas.long@intel.com>, "Ouyang,
	Changchun" <changchun.ouyang@intel.com>

On Tue, Sep 01, 2015 at 12:41:49PM +0300, Michael S. Tsirkin wrote:
> On Tue, Sep 01, 2015 at 05:20:06PM +0800, Yuanhan Liu wrote:
> > On Mon, Aug 31, 2015 at 02:30:06PM +0300, Michael S. Tsirkin wrote:
> > [snip..] 
> > > > Then how about the other case:
> > > > When startup the vhost backend, user specify 8 queues, like:
> > > > Vhost-user ...  -queues 8      # Y=8
> > > > When startup the guest, user specify 4 queues, like:
> > > > Qemu-kvm ... -queues 4      # X=4
> > > > 
> > > > Vhost backend CAN support the queues number as much as the guest/qemu requires,
> > > > And qemu don't want enable all of them(8 in the case), just part of them(only 4 from 8).
> > > > Will qemu exit or go forward(of course with 4 queues)? 
> > > 
> > > I think it must go forward since guest does not have to
> > > configure all queues anyway - and that's built in to virtio spec.
> > > 
> > > Note that # of queues in actual use in fact changes dynamically
> > > too, without restaring the device.
> > 
> > May I know how do you do that? I mean, is there a public interface, like
> > by some commands? Or, by sending vhost messages?
> > 
> > 	--yliu
> 
> Using ethtool within guest. In fact, guests boot with a single queue,
> you need to use ethtool to enable mq, specifying the # of queues.

Thanks for the info.

	--yliu