From: Paolo Abeni <pabeni@redhat•com>
To: netdev@vger•kernel.org
Cc: "David S. Miller" <davem@davemloft•net>,
Stephen Hemminger <stephen@networkplumber•org>,
Pravin Shelar <pshelar@nicira•com>,
Jesse Gross <jesse@kernel•org>, Flavio Leitner <fbl@sysclose•org>,
Hannes Frederic Sowa <hannes@stressinduktion•org>
Subject: Re: [PATCH net-next 4/5] net/tun: implement ndo_set_rx_headroom
Date: Thu, 25 Feb 2016 11:49:42 +0100 [thread overview]
Message-ID: <1456397382.5100.32.camel@redhat.com> (raw)
In-Reply-To: <38c29993e36ee3446f29a635c2d218e7777f55fe.1456163137.git.pabeni@redhat.com>
On Tue, 2016-02-23 at 13:53 +0100, Paolo Abeni wrote:
> 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 around 6% when tunneling over
> ipv6.
>
> In case of ipv4 tunnels there is no improvement, since the tun
> device default alignment provides enough headroom to avoid the skb
> head reallocation, at least on hosts with 64 bytes cacheline.
>
> Signed-off-by: Paolo Abeni <pabeni@redhat•com>
> ---
> drivers/net/tun.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 88bb8cc..5812693 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;
This needs to be initialized to NET_SKB_PAD, to preserved the current
behavior.
I'll fix it in v2.
Paolo
next prev parent reply other threads:[~2016-02-25 10:49 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-23 12:53 [PATCH net-next 0/5] bridge/ovs: avoid skb head copy on frame forwarding Paolo Abeni
2016-02-23 12:53 ` [PATCH net-next 1/5] netdev: introduce ndo_set_rx_headroom Paolo Abeni
2016-02-23 19:20 ` pravin shelar
2016-02-24 8:37 ` Paolo Abeni
2016-02-23 12:53 ` [PATCH net-next 2/5] bridge: notify ensabled devices of headroom changes Paolo Abeni
2016-02-23 19:20 ` pravin shelar
2016-02-24 8:43 ` Paolo Abeni
2016-02-23 12:53 ` [PATCH net-next 3/5] ovs: propagate per dp max headroom to all vports Paolo Abeni
2016-02-23 19:20 ` pravin shelar
2016-02-24 8:59 ` Paolo Abeni
2016-02-23 12:53 ` [PATCH net-next 4/5] net/tun: implement ndo_set_rx_headroom Paolo Abeni
2016-02-25 10:49 ` Paolo Abeni [this message]
2016-02-23 12:53 ` [PATCH net-next 5/5] veth: " Paolo Abeni
2016-02-23 19:21 ` pravin shelar
2016-02-24 9:17 ` Paolo Abeni
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