On 1/27/26 8:04 AM, Marek Mietus wrote:

Currently, tunnel xmit flows always take a reference on the dst_entry
for each xmitted packet. These atomic operations are redundant in some
flows.

This patchset introduces the infrastructure required for converting
the tunnel xmit flows to noref, and converts them where possible.

These changes improve tunnel performance, since less atomic operations
are used.

There are already noref optimizations in both ipv4 and ip6.
(See __ip_queue_xmit, inet6_csk_xmit)
This patchset implements similar optimizations in ip and udp tunnels.

Benchmarks:
I used a vxlan tunnel over a pair of veth peers and measured the average
throughput over multiple samples.

I ran 100 samples on a clean build, and another 100 on a patched
build. Each sample ran for 120 seconds. These were my results:

clean:      71.95 mb/sec, stddev = 1.71
patched:    74.92 mb/sec, stddev = 1.35

Which H/W are you using? I've never seen so low figures in this decade,
possibly not even in the previous one. Expected tput on not too
obsoleted H/W is orders of magnitude higher, and we need more relevant
figures.

Thanks,

Paolo