]> Git Repo - linux.git/commit - net/ipv6/ip6_output.c
ipv6: disable GSO on sockets hitting dst_allfrag
authorEric Dumazet <[email protected]>
Fri, 18 May 2012 21:51:44 +0000 (21:51 +0000)
committerDavid S. Miller <[email protected]>
Sat, 19 May 2012 08:02:12 +0000 (04:02 -0400)
commita34a101e1e6365638b02ea83a38d7a4cb228dc04
tree6757af0793572021c9284bccdae87a8a737e62ab
parenta1e8b307986ab27b7608f107aec71d3569650f46
ipv6: disable GSO on sockets hitting dst_allfrag

If the allfrag feature has been set on a host route (due to an ICMPv6
Packet Too Big received indicating a MTU of less than 1280), we hit a
very slow behavior in TCP stack, because all big packets are dropped and
only a retransmit timer is able to push one MSS frame every 200 ms.

One way to handle this is to disable GSO on the socket the first time a
super packet is dropped. Adding a specific dst_allfrag() in the fast
path is probably overkill since the dst_allfrag() case almost never
happen.

Result on netperf TCP_STREAM, one flow :

Before : 60 kbit/sec
After : 1.6 Gbit/sec

Reported-by: Tore Anderson <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Tested-by: Tore Anderson <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
net/ipv6/ip6_output.c
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