UDP: further performance improvements on tx
Cumulative throughput while running 64
netperf -H $DUT -t UDP_STREAM -- -m 1
on a 2x8x2 SKL went from 1.1Mpps to 2.5Mpps
Single stream throughput increases from 910kpps to 1.18Mpps
Baseline:
https://people.freebsd.org/~mmacy/2018.05.11/udpsender2.svg
- Protect read access to global ifnet list with epoch
https://people.freebsd.org/~mmacy/2018.05.11/udpsender3.svg
- Protect short lived ifaddr references with epoch
https://people.freebsd.org/~mmacy/2018.05.11/udpsender4.svg
- Convert if_afdata read lock path to epoch
https://people.freebsd.org/~mmacy/2018.05.11/udpsender5.svg
A fix for the inpcbhash contention is pending sufficient time
on a canary at LLNW.
Reviewed by: gallatin
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D15409