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veth: implement ndo_set_rx_headroom

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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: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2016-02-26 10:45:41 +01:00 committed by David S. Miller
parent eaea34b23c
commit 163e529200
1 changed files with 26 additions and 0 deletions
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26
drivers/net/veth.c
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@ -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;