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Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahea
From: |
Yuanhan Liu |
Subject: |
Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init |
Date: |
Thu, 10 Sep 2015 14:18:25 +0800 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
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 <address@hidden>
> >>>>> > >>> ---
> >>>>> > >>> 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.
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
- [Qemu-devel] [PATCH 0/7 v7] vhost-user multiple queue support, Yuanhan Liu, 2015/09/08
- [Qemu-devel] [PATCH 3/7] vhost: rename VHOST_RESET_OWNER to VHOST_RESET_DEVICE, Yuanhan Liu, 2015/09/08
- [Qemu-devel] [PATCH 4/7] vhost-user: add VHOST_USER_GET_QUEUE_NUM message, Yuanhan Liu, 2015/09/08
- [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init, Yuanhan Liu, 2015/09/08
- Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init, Jason Wang, 2015/09/09
- Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init, Yuanhan Liu, 2015/09/09
- Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init, Jason Wang, 2015/09/10
- Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init, Yuanhan Liu, 2015/09/10
- Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init, Jason Wang, 2015/09/10
- Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init,
Yuanhan Liu <=
- Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init, Jason Wang, 2015/09/10
- Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init, Yuanhan Liu, 2015/09/10
- Re: [Qemu-devel] [PATCH 5/7] vhost_net: move vhost_net_set_vq_index ahead at vhost_net_init, Yuanhan Liu, 2015/09/14
[Qemu-devel] [PATCH 1/7] vhost-user: use VHOST_USER_XXX macro for switch statement, Yuanhan Liu, 2015/09/08
[Qemu-devel] [PATCH 7/7] vhost-user: add a new message to disable/enable a specific virt queue., Yuanhan Liu, 2015/09/08