From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43329) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZZvkJ-0007DD-N1 for qemu-devel@nongnu.org; Thu, 10 Sep 2015 02:54:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZZvkE-00064T-IE for qemu-devel@nongnu.org; Thu, 10 Sep 2015 02:54:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43159) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZZvkE-00063z-9g for qemu-devel@nongnu.org; Thu, 10 Sep 2015 02:54:06 -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> <55F11A9E.8040303@redhat.com> <20150910061825.GR2925@yliu-dev.sh.intel.com> From: Jason Wang Message-ID: <55F1290A.1050208@redhat.com> Date: Thu, 10 Sep 2015 14:54:02 +0800 MIME-Version: 1.0 In-Reply-To: <20150910061825.GR2925@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: changchun.ouyang@intel.com, qemu-devel@nongnu.org, mst@redhat.com On 09/10/2015 02:18 PM, Yuanhan Liu wrote: > On Thu, Sep 10, 2015 at 01:52:30PM +0800, Jason Wang wrote: >> >> 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? > Yeah, I guess that's the difference between vhost-user and vhost-kernel. > Vhost-kernel opens a char device(/dev/vhost-net) for each vhost_dev, > hence it's distinguishable. But for vhost-user, all vhost_dev share one > char device(a socket) for communication, hence, it's not distinguishable. How about using individual socket in this case? This seems can also minimize the changes of backend. > > I was thinking maybe we could export vhost_net_set_vq_index() and invoke > it at net/vhost-user.c, so that we break nothing, and in the meantime, > it keeps the logic inside vhost-user. > > What do you think? > > --yliu > Sounds work. Then I believe you will need to set queue_index in vhost_user initialization code? Thanks