From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 28 Sep 2010 00:17:17 +0000 (+0000)
Subject: ipip: enable lockless xmits
X-Git-Tag: v2.6.37-rc1~147^2~313
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=153f0943382e9ae0bff7caa110a1a4656088d0d4;p=pandora-kernel.git

ipip: enable lockless xmits

IPIP tunnels can benefit from lockless xmits, using NETIF_F_LLTX

Bench on a 16 cpus machine (dual E5540 cpus), 16 threads sending
10000000 UDP frames via one ipip tunnel (size:200 bytes per frame)

Before patch :
real	2m53.321s
user	0m10.277s
sys	46m0.597s

After patch:
real	0m32.063s
user	0m9.237s
sys	8m16.255s

Last problem to solve is the contention on dst :

16118.00 28.3% __ip_route_output_key         vmlinux
 6135.00 10.8% dst_release                   vmlinux
 3220.00  5.6% ip_finish_output              vmlinux
 2149.00  3.8% ip_route_output_flow          vmlinux
 1575.00  2.8% ip_append_data                vmlinux
 1481.00  2.6% ip_push_pending_frames        vmlinux
 1349.00  2.4% __xfrm_lookup                 vmlinux
 1216.00  2.1% csum_partial_copy_generic     vmlinux
 1208.00  2.1% udp_sendmsg                   vmlinux

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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