[net-next,0/4] Add TCP fraglist GRO support

Message

Felix Fietkau April 24, 2024, 6:04 p.m. UTC

When forwarding TCP after GRO, software segmentation is very expensive,
especially when the checksum needs to be recalculated.
One case where that's currently unavoidable is when routing packets over
PPPoE. Performance improves significantly when using fraglist GRO
implemented in the same way as for UDP.

When NETIF_F_GRO_FRAGLIST is enabled, perform a lookup for an established
socket in the same netns as the receiving device. While this may not
cover all relevant use cases in multi-netns configurations, it should be
good enough for most configurations that need this.

Here's a measurement of running 2 TCP streams through a MediaTek MT7622
device (2-core Cortex-A53), which runs NAT with flow offload enabled from
one ethernet port to PPPoE on another ethernet port + cake qdisc set to
1Gbps.

rx-gro-list off: 630 Mbit/s, CPU 35% idle
rx-gro-list on:  770 Mbit/s, CPU 40% idle

Changes since RFC:
 - split up patches
 - handle TCP flags mutations

Felix Fietkau (4):
  net: move skb_gro_receive_list from udp to core
  net: add support for segmenting TCP fraglist GSO packets
  net: add code for TCP fraglist GRO
  net: add heuristic for enabling TCP fraglist GRO

 include/net/gro.h        |   1 +
 include/net/tcp.h        |   3 +-
 net/core/gro.c           |  27 ++++++++
 net/ipv4/tcp_offload.c   | 146 ++++++++++++++++++++++++++++++++++++++-
 net/ipv4/udp_offload.c   |  27 --------
 net/ipv6/tcpv6_offload.c |  92 +++++++++++++++++++++++-
 6 files changed, 265 insertions(+), 31 deletions(-)