Remove IPSEC from GENERIC due to performance issues

Having IPSEC compiled into the kernel imposes a non-trivial
performance penalty on multi-threaded workloads due to IPSEC
refcounting. In my benchmarks of multi-threaded UDP
transmit (connected sockets), I've seen a roughly 20% performance
penalty when the IPSEC option is included in the kernel (16.8Mpps
vs 13.8Mpps with 32 senders on a 14 core / 28 HTT Xeon
2697v3)). This is largely due to key_addref() incrementing and
decrementing an atomic reference count on the default
policy. This cause all CPUs to stall on the same cacheline, as it
bounces between different CPUs.

Given that relatively few users use ipsec, and that it can be
loaded as a module, it seems reasonable to ask those users to
load the ipsec module so as to avoid imposing this penalty on the
GENERIC kernel. Its my hope that this will make FreeBSD look
better in "out of the box" benchmark comparisons with other
operating systems.

Many thanks to ae for fixing auto-loading of ipsec.ko when
ifconfig tries to configure ipsec, and to cy for volunteering
to ensure the the racoon ports will load the ipsec.ko module

Reviewed by:	cem, cy, delphij, gnn, jhb, jpaetzel
Differential Revision:	https://reviews.freebsd.org/D20163

1 files changed, 0 insertions, 1 deletions

diff --git a/sys/riscv/conf/GENERIC b/sys/riscv/conf/GENERIC
index 4b692415a194..7c2571f4783b 100644
--- a/sys/riscv/conf/GENERIC
+++ b/sys/riscv/conf/GENERIC
@@ -34,7 +34,6 @@ options 	VIMAGE			# Subsystem virtualization, e.g. VNET
 options 	INET			# InterNETworking
 options 	INET6			# IPv6 communications protocols
 options 	TCP_HHOOK		# hhook(9) framework for TCP
-options 	IPSEC			# IP (v4/v6) security
 options 	IPSEC_SUPPORT		# Allow kldload of ipsec and tcpmd5
 options 	TCP_OFFLOAD		# TCP offload
 options 	SCTP			# Stream Control Transmission Protocol