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
