From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58054) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZZumk-0007a3-SQ for qemu-devel@nongnu.org; Thu, 10 Sep 2015 01:52:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZZumh-0001v9-KO for qemu-devel@nongnu.org; Thu, 10 Sep 2015 01:52:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59156) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZZumh-0001ut-CO for qemu-devel@nongnu.org; Thu, 10 Sep 2015 01:52:35 -0400 References: <1441697927-16456-1-git-send-email-yuanhan.liu@linux.intel.com> <1441697927-16456-6-git-send-email-yuanhan.liu@linux.intel.com> <55F0F593.9030408@redhat.com> <20150910035702.GP2925@yliu-dev.sh.intel.com> <55F10B08.1060707@redhat.com> <20150910051735.GQ2925@yliu-dev.sh.intel.com> From: Jason Wang Message-ID: <55F11A9E.8040303@redhat.com> Date: Thu, 10 Sep 2015 13:52:30 +0800 MIME-Version: 1.0 In-Reply-To: <20150910051735.GQ2925@yliu-dev.sh.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Yuanhan Liu Cc: mst@redhat.com, qemu-devel@nongnu.org, changchun.ouyang@intel.com On 09/10/2015 01:17 PM, Yuanhan Liu wrote: > On Thu, Sep 10, 2015 at 12:46:00PM +0800, Jason Wang wrote: >> > >> > >> > On 09/10/2015 11:57 AM, Yuanhan Liu wrote: >>> > > On Thu, Sep 10, 2015 at 11:14:27AM +0800, Jason Wang wrote: >>>> > >> >>>> > >> On 09/08/2015 03:38 PM, Yuanhan Liu wrote: >>>>> > >>> So that we could use the `vq_index' as well in the vhost_net_init >>>>> > >>> stage, which is required when adding vhost-user multiple-queue support, >>>>> > >>> where we need the vq_index to indicate which queue pair we are gonna >>>>> > >>> initiate. >>>>> > >>> >>>>> > >>> vhost-user has no multiple queue support yet, hence no queue_index set >>>>> > >>> before. Here is a quick set to 0 at net_vhost_user_init() stage, and it >>>>> > >>> will be set properly soon in the next patch. >>>>> > >>> >>>>> > >>> Signed-off-by: Yuanhan Liu >>>>> > >>> --- >>>>> > >>> hw/net/vhost_net.c | 16 +++++++--------- >>>>> > >>> net/vhost-user.c | 1 + >>>>> > >>> 2 files changed, 8 insertions(+), 9 deletions(-) >>>>> > >>> >>>>> > >>> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c >>>>> > >>> index f9441e9..141b557 100644 >>>>> > >>> --- a/hw/net/vhost_net.c >>>>> > >>> +++ b/hw/net/vhost_net.c >>>>> > >>> @@ -138,6 +138,11 @@ static int vhost_net_get_fd(NetClientState *backend) >>>>> > >>> } >>>>> > >>> } >>>>> > >>> >>>>> > >>> +static void vhost_net_set_vq_index(struct vhost_net *net, int vq_index) >>>>> > >>> +{ >>>>> > >>> + net->dev.vq_index = vq_index; >>>>> > >>> +} >>>>> > >>> + >>>>> > >>> struct vhost_net *vhost_net_init(VhostNetOptions *options) >>>>> > >>> { >>>>> > >>> int r; >>>>> > >>> @@ -167,6 +172,8 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options) >>>>> > >>> } >>>>> > >>> net->nc = options->net_backend; >>>>> > >>> >>>>> > >>> + vhost_net_set_vq_index(net, net->nc->queue_index * 2); >>>>> > >>> + >>>> > >> This breaks vhost kernel multiqueue since queue_index was not >>>> > >> initialized at this time. >>> > > Right, thanks for pointing it out. >>> > > >>>> > >> We do this in set_netdev() instead of setting >>>> > >> it in each kind of netdev. >>> > > Can we move it to net_init_tap() for setting the right queue_index >>> > > for each nc? >>> > > >>> > > Or, can we call vhost_net_set_vq_index twice, one at vhost_net_init(for >>> > > vhost-user mq support), another one at vhost_net_start(for vhost kernel >>> > > mq support)? >>> > > >>> > > Or, do you have better ideas? >> > >> > I think setting queue_index in net_init_tap() looks ok. > Good to know. > >> > But a question >> > is that why need we do this at so early stage? ( Even before its peers >> > is connected.) > For vhost-user multiple queues support, we will invoke vhost_net_init() > N times for each queue pair, and hence we need to distinguish which > queue it is while sending messages like VHOST_SET_VRING_CALL for > initializing corresponding queue pair. > > Does that make sense to you? > Not sure. Since current codes works for vhost-kernel. (vhost_net_init() was also called N times). We don't want to break existed vhost-kernel API when developing multiqueue. For each virtqueue TX/RX pair, we have one vhost net device and it has no knowledge for the others (which was hide by qemu). So VHOST_SET_VRING_CALL works without any change here. For the case here, since you still have multiple instances of vhost_net structure. Maybe the vhost-user backend can distinguish form this?