K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2019-08-28T19:40:57.054637Z
K 7
svn:log
V 497
amd64: clean up cpu_switch.S

- LK macro (conditional on SMP for the lock prefix) is unused
- SETLK unnecessarily performs xchg. obtained value is never used and the
  implicit lock prefix adds avoidable cost. Barrier provided by it does
  not appear to be of any use.
- the lock waited for is almost never blocked, yet the loop starts with
  a pause. Move it out of the common case.

Reviewed by:	kib
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D19563

END