[ovs-dev] [PATCH dpdk-latest v2 0/4] Add support for TSO with DPDK

[Flavio Leitner]

Abbreviated as TSO, TCP Segmentation Offload is a feature which enables
the network stack to delegate the TCP segmentation to the NIC reducing
the per packet CPU overhead.

A guest using vhost-user interface with TSO enabled can send TCP packets
much bigger than the MTU, which saves CPU cycles normally used to break
the packets down to MTU size and to calculate checksums.

It also saves CPU cycles used to parse multiple packets/headers during
the packet processing inside virtual switch.

If the destination of the packet is another guest in the same host, then
the same big packet can be sent through a vhost-user interface skipping
the segmentation completely. However, if the destination is not local,
the NIC hardware is instructed to do the TCP segmentation and checksum
calculation.

The first 3 patches are not really part of TSO support, but they are
required to make sure everything works.

The TSO is enabled in the vhost-user ports in client mode and linux ports
in userspace.

This patchset is based on branch dpdk-latest (v19.11 required).

There are good improvements sending to or receiving from veth pairs or
tap devices as well.

Flavio Leitner (4):
  dp-packet: preserve headroom when cloning a pkt batch
  vhost: Disable multi-segmented buffers
  dp-packet: handle new dpdk buffer flags
  netdev-dpdk: Add TCP Segmentation Offload support

 Documentation/automake.mk           |   1 +
 Documentation/topics/dpdk/index.rst |   1 +
 Documentation/topics/dpdk/tso.rst   |  89 ++++++++
 NEWS                                |   1 +
 lib/automake.mk                     |   2 +
 lib/conntrack.c                     |  29 ++-
 lib/dp-packet.c                     |   4 +-
 lib/dp-packet.h                     | 160 +++++++++++++-
 lib/ipf.c                           |  32 +--
 lib/netdev-dpdk.c                   | 317 ++++++++++++++++++++++++----
 lib/netdev-linux-private.h          |   4 +
 lib/netdev-linux.c                  | 295 +++++++++++++++++++++++---
 lib/netdev-provider.h               |  10 +
 lib/netdev.c                        |  52 ++++-
 lib/tso.c                           |  54 +++++
 lib/tso.h                           |  23 ++
 vswitchd/bridge.c                   |   2 +
 vswitchd/vswitch.xml                |  12 ++
 18 files changed, 997 insertions(+), 91 deletions(-)
 create mode 100644 Documentation/topics/dpdk/tso.rst
 create mode 100644 lib/tso.c
 create mode 100644 lib/tso.h

-- 
2.24.1