On 12/31/2019 8:14 PM, Flavio Leitner wrote:
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).
Thanks for the patch Flavio, FYI 19.11 support is now upstreamed to OVS master. For future revisions to the patch series can you target master branch instead of dpdk-latest?
Ian
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
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