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Commit 163e5292 authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

veth: implement ndo_set_rx_headroom 



The rx headroom for veth dev is the peer device needed_headroom.
Avoid ping-pong updates setting the private flag IFF_PHONY_HEADROOM.

This avoids skb head reallocation when forwarding from a veth dev
towards a device adding some kind of encapsulation.

When transmitting frames below the MTU size towards a vxlan device,
this gives about 10% performance speed-up when OVS is used to connect
the veth and the vxlan device and a little more when using a
plain Linux bridge.

Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent eaea34b2

drivers/net/veth.c

+26 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ struct pcpu_vstats { 
struct veth_priv {

	struct net_device __rcu	*peer;

	atomic64_t		dropped;

	unsigned		requested_headroom;

};



/*
@@ -271,6 +272,29 @@ static int veth_get_iflink(const struct net_device *dev) 
	return iflink;

}



static void veth_set_rx_headroom(struct net_device *dev, int new_hr)

{

	struct veth_priv *peer_priv, *priv = netdev_priv(dev);

	struct net_device *peer;



	if (new_hr < 0)

		new_hr = 0;



	rcu_read_lock();

	peer = rcu_dereference(priv->peer);

	if (unlikely(!peer))

		goto out;



	peer_priv = netdev_priv(peer);

	priv->requested_headroom = new_hr;

	new_hr = max(priv->requested_headroom, peer_priv->requested_headroom);

	dev->needed_headroom = new_hr;

	peer->needed_headroom = new_hr;



out:

	rcu_read_unlock();

}



static const struct net_device_ops veth_netdev_ops = {

	.ndo_init            = veth_dev_init,

	.ndo_open            = veth_open,
@@ -285,6 +309,7 @@ static const struct net_device_ops veth_netdev_ops = { 
#endif

	.ndo_get_iflink		= veth_get_iflink,

	.ndo_features_check	= passthru_features_check,

	.ndo_set_rx_headroom	= veth_set_rx_headroom,

};



#define VETH_FEATURES (NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_ALL_TSO |    \
@@ -301,6 +326,7 @@ static void veth_setup(struct net_device *dev) 
	dev->priv_flags &= ~IFF_TX_SKB_SHARING;

	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;

	dev->priv_flags |= IFF_NO_QUEUE;

	dev->priv_flags |= IFF_PHONY_HEADROOM;



	dev->netdev_ops = &veth_netdev_ops;

	dev->ethtool_ops = &veth_ethtool_ops;