[PATCH v4 net-next 0/2] udp_tunnel: GRO optimizations

Paolo Abeni
2025-03-11T20:42:47Z

The UDP tunnel GRO stage is source of measurable overhead for workload
based on UDP-encapsulated traffic: each incoming packets requires a full
UDP socket lookup and an indirect call.

In the most common setups a single UDP tunnel device is used. In such
case we can optimize both the lookup and the indirect call.

Patch 1 tracks per netns the active UDP tunnels and replaces the socket
lookup with a single destination port comparison when possible.

Patch 2 tracks the different types of UDP tunnels and replaces the
indirect call with a static one when there is a single UDP tunnel type
active.

I measure ~5% performance improvement in TCP over UDP tunnel stream
tests on top of this series.
---
v3 -> v4:
- cleanup lookup in patch 2
- more RCU_INIT_POINTER usage in patch 1
(see the individual patches changelog for more details)
v3: https://lore.kernel.org/netdev/cover.1741632298.git.pabeni@redhat.com

v2 -> v3:
- avoid unneeded checks in udp_tunnel_update_gro_rcv()
- use RCU_INIT_POINTER() when possible
- drop 'inline' from c file
v2: https://lore.kernel.org/netdev/cover.1741338765.git.pabeni@redhat.com/

v1 -> v2:
- fixed a couple of typos
- fixed UDP_TUNNEL=n build
- clarified design choices
(see the individual patches changelog for more details)
v1: https://lore.kernel.org/netdev/cover.1741275846.git.pabeni@redhat.com/

Paolo Abeni (2):
udp_tunnel: create a fastpath GRO lookup.
udp_tunnel: use static call for GRO hooks when possible

include/linux/udp.h | 16 ++++
include/net/netns/ipv4.h | 11 +++
include/net/udp.h | 1 +
include/net/udp_tunnel.h | 22 +++++
net/ipv4/udp.c | 13 ++-
net/ipv4/udp_offload.c | 167 ++++++++++++++++++++++++++++++++++++-
net/ipv4/udp_tunnel_core.c | 14 ++++
net/ipv6/udp.c | 2 +
net/ipv6/udp_offload.c | 5 ++
9 files changed, 249 insertions(+), 2 deletions(-)

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2.48.1