[Cake] Fwd: [PATCH net-next 0/4] TC: refactor act_mirred packets re-injection

Dave Taht dave.taht at gmail.com
Thu Jul 19 09:12:12 EDT 2018

It looks like backporting this to openwrt would be a pita, but a
potential 10% improvement to inbound shaping is not to be sneezed at
(and I imagine it could be better than that for non-intel
cache-crippled routers)

---------- Forwarded message ---------
From: Paolo Abeni <pabeni at redhat.com>
Date: Thu, Jul 19, 2018 at 6:04 AM
Subject: [PATCH net-next 0/4] TC: refactor act_mirred packets re-injection
To: <netdev at vger.kernel.org>
Cc: Jamal Hadi Salim <jhs at mojatatu.com>, Cong Wang
<xiyou.wangcong at gmail.com>, Jiri Pirko <jiri at resnulli.us>, Daniel
Borkmann <daniel at iogearbox.net>, Marcelo Ricardo Leitner
<marcelo.leitner at gmail.com>, Eyal Birger <eyal.birger at gmail.com>

This series is aimed at improving the act_mirred redirect performances.
Such action is used by OVS to represent TC S/W flows, and it's current largest
bottle-neck is the need for a skb_clone() for each packet.

The first 2 patches introduce some cleanup and safeguards to allow extending
tca_result: we will use it to store RCU protected redirect information.
Then a new tca_action value is introduced: TC_ACT_MIRRED, similar to
TC_ACT_REDIRECT, but preserving the mirred semantic. The last patch exploits
the introduced infrastructure in the act_mirred action, to avoid a skb_clone,
when possible.

Overall this the above gives a ~10% performance improvement in forwarding tput,
when using the TC S/W datapath.

v1 -> v2:
 - preserve the rcu lock in act_bpf
 - add and use a new action value to reinject the packets, preserving the mirred

Paolo Abeni (4):
  tc/act: user space can't use TC_ACT_REDIRECT directly
  tc/act: remove unneeded RCU lock in action callback
  net/tc: introduce TC_ACT_MIRRED.
  act_mirred: use ACT_MIRRED when possible

 include/net/act_api.h        |  2 +-
 include/net/sch_generic.h    | 21 +++++++++++++++++++++
 include/uapi/linux/pkt_cls.h |  2 ++
 net/core/dev.c               |  4 ++++
 net/sched/act_api.c          |  7 +++++++
 net/sched/act_csum.c         | 12 +++---------
 net/sched/act_ife.c          |  5 +----
 net/sched/act_mirred.c       | 35 +++++++++++++++++++++++------------
 net/sched/act_sample.c       |  4 +---
 net/sched/act_skbedit.c      | 10 +++-------
 net/sched/act_skbmod.c       | 21 +++++++++------------
 net/sched/act_tunnel_key.c   |  6 +-----
 net/sched/act_vlan.c         | 19 +++++++------------
 13 files changed, 83 insertions(+), 65 deletions(-)



Dave Täht
CEO, TekLibre, LLC
Tel: 1-669-226-2619

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