Subject: Re: [PATCH net-next 3/5] ovs: propagate per dp max headroom to all vports

From: Paolo Abeni <[email-masked]>
Date: Wed, 24 Feb 2016 09:59:07 +0100

On Tue, 2016-02-23 at 11:20 -0800, pravin shelar wrote:
> On Tue, Feb 23, 2016 at 4:53 AM, Paolo Abeni <[email-masked]> wrote:
> > This patch implements bookkeeping support to compute the maximum
> > headroom for all the devices in each datapath. When said value
> > changes, the underlying devs are notified via the
> > ndo_set_rx_headroom method.
> >
> > This also increases the internal vports xmit performance.
> >
> > Signed-off-by: Paolo Abeni <[email-masked]>
> > ---
> >  net/openvswitch/datapath.c           | 48 ++++++++++++++++++++++++++++++++++++
> >  net/openvswitch/datapath.h           |  4 +++
> >  net/openvswitch/vport-internal_dev.c | 10 +++++++-
> >  3 files changed, 61 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> > index c4e8455..7b37288 100644
> > --- a/net/openvswitch/datapath.c
> > +++ b/net/openvswitch/datapath.c
> > @@ -1908,6 +1908,34 @@ static struct vport *lookup_vport(struct net *net,
> >                 return ERR_PTR(-EINVAL);
> >  }
> >
> > +/* Called with ovs_mutex */
> > +static void update_headroom(struct datapath *dp)
> > +{
> > +       int i;
> > +       struct vport *vport;
> > +       struct net_device *dev;
> > +       unsigned dev_headroom, max_headroom = 0;
> > +
> > +       for (i = 0; i < DP_VPORT_HASH_BUCKETS; i++) {
> > +               hlist_for_each_entry_rcu(vport, &dp->ports[i], dp_hash_node) {
> > +                       dev = vport->dev;
> > +                       dev_headroom = netdev_get_fwd_headroom(dev);
> > +                       if (dev_headroom > max_headroom)
> > +                               max_headroom = dev_headroom;
> > +               }
> > +       }
> > +
> > +       dp->max_headroom = max_headroom;
> > +       for (i = 0; i < DP_VPORT_HASH_BUCKETS; i++) {
> > +               hlist_for_each_entry_rcu(vport, &dp->ports[i], dp_hash_node) {
> > +                       dev = vport->dev;
> > +                       if (dev->netdev_ops->ndo_set_rx_headroom)
> > +                               dev->netdev_ops->ndo_set_rx_headroom(dev,
> > +                                                                 max_headroom);
> > +               }
> > +       }
> > +}
> > +
> Code looks fine. But It could be kept in sync with bridge code from patch 2.

You are right. 

I can had an helper to wrap the conditional ndo_set_rx_headroom()
invocation, so that all the code here and in the bridge will be devices
traversal only.

Paolo