mbox series

[Openvpn-devel,net-next,v3,0/3] net: tunnel: introduce noref xmit flows for tunnels

Message ID 20250922110622.10368-1-mmietus97@yahoo.com
Headers show
Series net: tunnel: introduce noref xmit flows for tunnels | expand

Message

Marek Mietus Sept. 22, 2025, 11:06 a.m. UTC 
Currently, all xmit flows use dst_cache in a way that references
its dst_entry for each xmitted packet. These atomic operations
are redundant in some flows.

This patchset introduces new noref xmit helpers and incorporates
them in the OpenVPN driver. A similar improvement can also be
applied to other tunnel code in the future. The implementation
for OpenVPN is a good starting point as it doesn't use the
udp_tunnel_dst_lookup helper which adds some complexity.

There are already noref optimizations in both ipv4 and ip6 
(See __ip_queue_xmit, inet6_csk_xmit). This patchset allows for
similar optimizations in udp tunnels. Referencing the dst_entry
is now redundant, as the entire flow is protected under RCU, so
it is removed.

With this patchset, I was able to observe a 4% decrease in the total
time for ovpn_udp_send_skb using perf.

Changes in v3:
 - Added implementation for ip6
 - Updated cover letter and commit messages

Link to v2: https://lore.kernel.org/netdev/20250912112420.4394-1-mmietus97@yahoo.com/