[PATCH net-next-2.6 0/4] tunnels: SMP safe accounting

[PATCH net-next-2.6 0/4] tunnels: SMP safe accounting

[Eric Dumazet]

Before making ip_gre, ipip, and sit transmit path lockless, it is
necessary to make accounting SMP safe, not only for correctness but to
avoid cache line ping pongs.

This also takes care of receive path, already lockless and using unsafe
stats accounting.

I chose to use small percpu structures, holding {rx|tx}_{packets|bytes}
only, and keep all other counters in netdev->stats, since they should be
seldom used.

Patch 1/4 makes the needed changes in include files
Patch 2/4 takes care of ip_gre
Patch 3/4 takes care of ipip
Patch 4/4 takes care of sit

Thanks

 include/linux/netdevice.h |    1 
 include/net/dst.h         |   24 ++++--
 include/net/ipip.h        |   12 +--
 net/ipv4/ip_gre.c         |  138 +++++++++++++++++++++++++-----------
 net/ipv4/ipip.c           |  127 ++++++++++++++++++++++++---------
 net/ipv6/sit.c            |   80 ++++++++++++++++----
 6 files changed, 282 insertions(+), 100 deletions(-)

Re: [PATCH net-next-2.6 0/4] tunnels: SMP safe accounting

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 27 Sep 2010 12:32:48 +0200

> Before making ip_gre, ipip, and sit transmit path lockless, it is
> necessary to make accounting SMP safe, not only for correctness but to
> avoid cache line ping pongs.
> 
> This also takes care of receive path, already lockless and using unsafe
> stats accounting.
> 
> I chose to use small percpu structures, holding {rx|tx}_{packets|bytes}
> only, and keep all other counters in netdev->stats, since they should be
> seldom used.

Series applied, thanks a lot Eric!