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authorPaolo Abeni <pabeni@redhat.com>2016-02-26 12:45:40 +0300
committerDavid S. Miller <davem@davemloft.net>2016-03-01 23:54:30 +0300
commiteaea34b23c46bf17b4a5638be69ab3561854f34b (patch)
tree1a2182f40f905d60de941bda9513864eb22fe9ab /drivers/net/tun.c
parent3a927bc7cf9d0fbe8f4a8189dd5f8440228f64e7 (diff)
downloadlinux-eaea34b23c46bf17b4a5638be69ab3561854f34b.tar.xz
net/tun: implement ndo_set_rx_headroom
ndo_set_rx_headroom controls the align value used by tun devices to allocate skbs on frame reception. When the xmit device adds a large encapsulation, this avoids an skb head reallocation on forwarding. The measured improvement when forwarding towards a vxlan dev with frame size below the egress device MTU is as follow: vxlan over ipv6, bridged: +6% vxlan over ipv6, ovs: +7% In case of ipv4 tunnels there is no improvement, since the tun device default alignment provides enough headroom to avoid the skb head reallocation. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/tun.c')
-rw-r--r--drivers/net/tun.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 88bb8cc3555b..afdf950617c3 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -187,6 +187,7 @@ struct tun_struct {
#define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
NETIF_F_TSO6|NETIF_F_UFO)
+ int align;
int vnet_hdr_sz;
int sndbuf;
struct tap_filter txflt;
@@ -934,6 +935,17 @@ static void tun_poll_controller(struct net_device *dev)
return;
}
#endif
+
+static void tun_set_headroom(struct net_device *dev, int new_hr)
+{
+ struct tun_struct *tun = netdev_priv(dev);
+
+ if (new_hr < NET_SKB_PAD)
+ new_hr = NET_SKB_PAD;
+
+ tun->align = new_hr;
+}
+
static const struct net_device_ops tun_netdev_ops = {
.ndo_uninit = tun_net_uninit,
.ndo_open = tun_net_open,
@@ -945,6 +957,7 @@ static const struct net_device_ops tun_netdev_ops = {
#ifdef CONFIG_NET_POLL_CONTROLLER
.ndo_poll_controller = tun_poll_controller,
#endif
+ .ndo_set_rx_headroom = tun_set_headroom,
};
static const struct net_device_ops tap_netdev_ops = {
@@ -962,6 +975,7 @@ static const struct net_device_ops tap_netdev_ops = {
.ndo_poll_controller = tun_poll_controller,
#endif
.ndo_features_check = passthru_features_check,
+ .ndo_set_rx_headroom = tun_set_headroom,
};
static void tun_flow_init(struct tun_struct *tun)
@@ -1086,7 +1100,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
struct sk_buff *skb;
size_t total_len = iov_iter_count(from);
- size_t len = total_len, align = NET_SKB_PAD, linear;
+ size_t len = total_len, align = tun->align, linear;
struct virtio_net_hdr gso = { 0 };
int good_linear;
int copylen;
@@ -1694,6 +1708,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
tun->txflt.count = 0;
tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
+ tun->align = NET_SKB_PAD;
tun->filter_attached = false;
tun->sndbuf = tfile->socket.sk->sk_sndbuf;