[PATCH net v2] geneve: initialize needed_headroom

[PATCH net v2] geneve: initialize needed_headroom

[Paolo Abeni]

Currently the needed_headroom field for the geneve device is left
to the default value.

This patch set it to space required for basic geneve encapsulation,
so that we can avoid the skb head re-allocation on xmit.

This give a 6% speedup for unsegment traffic on geneve tunnel.

v1 -> v2:
  - add ETH_HLEN for the lower device to the needed headroom

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 drivers/net/geneve.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index c2b79f5..58efdec 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -1155,7 +1155,7 @@ static int geneve_configure(struct net *net, struct net_device *dev,
 	struct geneve_net *gn = net_generic(net, geneve_net_id);
 	struct geneve_dev *t, *geneve = netdev_priv(dev);
 	bool tun_collect_md, tun_on_same_port;
-	int err;
+	int err, encap_len;
 
 	if (!remote)
 		return -EINVAL;
@@ -1187,6 +1187,14 @@ static int geneve_configure(struct net *net, struct net_device *dev,
 	if (t)
 		return -EBUSY;
 
+	/* make enough headroom for basic scenario */
+	encap_len = GENEVE_BASE_HLEN + ETH_HLEN;
+	if (remote->sa.sa_family == AF_INET)
+		encap_len += sizeof(struct iphdr);
+	else
+		encap_len += sizeof(struct ipv6hdr);
+	dev->needed_headroom = encap_len + ETH_HLEN;
+
 	if (metadata) {
 		if (tun_on_same_port)
 			return -EPERM;
-- 
1.8.3.1

Re: [PATCH net v2] geneve: initialize needed_headroom

[John W. Linville]

On Wed, Dec 23, 2015 at 04:54:27PM +0100, Paolo Abeni wrote:
> Currently the needed_headroom field for the geneve device is left
> to the default value.
> 
> This patch set it to space required for basic geneve encapsulation,
> so that we can avoid the skb head re-allocation on xmit.
> 
> This give a 6% speedup for unsegment traffic on geneve tunnel.
> 
> v1 -> v2:
>   - add ETH_HLEN for the lower device to the needed headroom
> 
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>

This time I really mean it... ;-)

Acked-by: John W. Linville <linville@tuxdriver.com>

-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.

Re: [PATCH net v2] geneve: initialize needed_headroom

[David Miller]

From: Paolo Abeni <pabeni@redhat.com>
Date: Wed, 23 Dec 2015 16:54:27 +0100

> Currently the needed_headroom field for the geneve device is left
> to the default value.
> 
> This patch set it to space required for basic geneve encapsulation,
> so that we can avoid the skb head re-allocation on xmit.
> 
> This give a 6% speedup for unsegment traffic on geneve tunnel.
> 
> v1 -> v2:
>   - add ETH_HLEN for the lower device to the needed headroom
> 
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>

Applied, thank you.