accept(2)/close(2) performance on DragonFly-1ae4ae5

[Sepherosa Ziehau]

The network configuration and various settings (tunables/sysctls) are same as:
http://lists.dragonflybsd.org/pipermail/users/2016-May/249647.html

The accept(2)/close(2) performance is measured w/:
http://gitweb.dragonflybsd.org/dragonfly.git/tree/HEAD:/tools/tools/netrate/accept_connect/kq_accept_server
http://gitweb.dragonflybsd.org/dragonfly.git/tree/HEAD:/tools/tools/netrate/accept_connect/kq_connect_client

Server side runs:
kq_accept_server -p 7000 -i 16 -r -B (SO_REUSEPORT and process CPU
binding according to getsockopt(SOL_SOCKET,SO_CPUHINT))

Two clients run the following command at the same time:
kq_connect_client -4 ADDR -p 7000 -i 8 -c X -l 600 -B (X = {64,128,256,512})

The result (600s average):
1024 concurrent connections: 494Kconns/s
2048 concurrent connections: 514Kconns/s
4096 concurrent connections: 576Kconns/s
8192 concurrent connections: 580Kconns/s

Contention rate is pretty low (1000/s ~ 2000/s).  Almost no CPU time
is left on CPUs having netisrs @8192 concurrent connections, but the
system is pretty responsive and systat output is smooth.

Thanks,
sephe

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