Date:   Thu, 14 Jun 2018 16:19:34 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     netdev@...r.kernel.org, steffen.klassert@...unet.com
Subject: [PATCH net-next,RFC 00/13] New fast forwarding path

Hi,

This patchset proposes a new fast forwarding path infrastructure that
combines the GRO/GSO and the flowtable infrastructures. The idea is to
add a hook at the GRO layer that is invoked before the standard GRO
protocol offloads. This allows us to build custom packet chains that we
can quickly pass in one go to the neighbour layer to define fast
forwarding path for flows.

For each packet that gets into the GRO layer, we first check if there is
an entry in the flowtable, if so, the packet is placed in a list until
the GRO infrastructure decides to send the batch from gro_complete to
the neighbour layer. The first packet in the list takes the route from
the flowtable entry, so we avoid reiterative routing lookups.

In case no entry is found in the flowtable, the packet is passed up to
the classic GRO offload handlers. Thus, this packet follows the standard
forwarding path. Note that the initial packets of the flow always go
through the standard IPv4/IPv6 netfilter forward hook, that is used to
configure what flows are placed in the flowtable. Therefore, only a few
(initial) packets follow the standard forwarding path while most of the
follow up packets take this new fast forwarding path.

The fast forwarding path is enabled through explicit user policy, so the
user needs to request this behaviour from control plane, the following
example shows how to place flows in the new fast forwarding path from
the netfilter forward chain:

 table x {
        flowtable f {
                hook early_ingress priority 0; devices = { eth0, eth1 }
        }

        chain y {
                type filter hook forward priority 0;
                ip protocol tcp flow offload @f
        }
 }

The example above defines a fastpath for TCP flows that are placed in
the flowtable 'f', this flowtable is hooked at the new early_ingress
hook. The initial TCP packets that match this rule from the standard
fowarding path create an entry in the flowtable, thus, GRO creates chain
of packets for those that find an entry in the flowtable and send
them through the neighbour layer.

This new hook is happening before the ingress taps, therefore, packets
that follow this new fast forwarding path are not shown by tcpdump.

This patchset supports both layer 3 IPv4 and IPv6, and layer 4 TCP and
UDP protocols. This fastpath also integrates with the IPSec
infrastructure and the ESP protocol.

We have collected performance numbers:

        TCP TSO         TCP Fast Forward
        32.5 Gbps       35.6 Gbps

        UDP             UDP Fast Forward
        17.6 Gbps       35.6 Gbps

        ESP             ESP Fast Forward
        6 Gbps          7.5 Gbps

For UDP, this is doubling performance, and we almost achieve line rate
with one single CPU using the Intel i40e NIC. We got similar numbers
with the Mellanox ConnectX-4. For TCP, this is slightly improving things
even if TSO is being defeated given that we need to segment the packet
chain in software. We would like to explore HW GRO support with hardware
vendors with this new mode, we think that should improve the TCP numbers
we are showing above even more. For ESP traffic, performance improvement
is ~25%, in this case, perf shows the bottleneck becomes the crypto layer.

This patchset is co-authored work with Steffen Klassert.

Comments are welcome, thanks.


Pablo Neira Ayuso (6):
  netfilter: nft_chain_filter: add support for early ingress
  netfilter: nf_flow_table: add hooknum to flowtable type
  netfilter: nf_flow_table: add flowtable for early ingress hook
  netfilter: nft_flow_offload: enable offload after second packet is seen
  netfilter: nft_flow_offload: remove secpath check
  netfilter: nft_flow_offload: make sure route is not stale

Steffen Klassert (7):
  net: Add a helper to get the packet offload callbacks by priority.
  net: Change priority of ipv4 and ipv6 packet offloads.
  net: Add a GSO feature bit for the netfilter forward fastpath.
  net: Use one bit of NAPI_GRO_CB for the netfilter fastpath.
  netfilter: add early ingress hook for IPv4
  netfilter: add early ingress support for IPv6
  netfilter: add ESP support for early ingress

 include/linux/netdev_features.h         |   4 +-
 include/linux/netdevice.h               |   6 +-
 include/linux/netfilter.h               |   6 +
 include/linux/netfilter_ingress.h       |   1 +
 include/linux/skbuff.h                  |   2 +
 include/net/netfilter/early_ingress.h   |  24 +++
 include/net/netfilter/nf_flow_table.h   |   4 +
 include/uapi/linux/netfilter.h          |   1 +
 net/core/dev.c                          |  50 ++++-
 net/ipv4/af_inet.c                      |   1 +
 net/ipv4/netfilter/Makefile             |   1 +
 net/ipv4/netfilter/early_ingress.c      | 327 +++++++++++++++++++++++++++++
 net/ipv4/netfilter/nf_flow_table_ipv4.c |  12 ++
 net/ipv6/ip6_offload.c                  |   1 +
 net/ipv6/netfilter/Makefile             |   1 +
 net/ipv6/netfilter/early_ingress.c      | 315 ++++++++++++++++++++++++++++
 net/ipv6/netfilter/nf_flow_table_ipv6.c |   1 +
 net/netfilter/Kconfig                   |   8 +
 net/netfilter/Makefile                  |   1 +
 net/netfilter/core.c                    |  35 +++-
 net/netfilter/early_ingress.c           | 361 ++++++++++++++++++++++++++++++++
 net/netfilter/nf_flow_table_inet.c      |   1 +
 net/netfilter/nf_flow_table_ip.c        |  72 +++++++
 net/netfilter/nf_tables_api.c           | 120 ++++++-----
 net/netfilter/nft_chain_filter.c        |   6 +-
 net/netfilter/nft_flow_offload.c        |  13 +-
 net/xfrm/xfrm_output.c                  |   4 +
 27 files changed, 1297 insertions(+), 81 deletions(-)
 create mode 100644 include/net/netfilter/early_ingress.h
 create mode 100644 net/ipv4/netfilter/early_ingress.c
 create mode 100644 net/ipv6/netfilter/early_ingress.c
 create mode 100644 net/netfilter/early_ingress.c

-- 
2.11.0

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