1.1170

t NOTES i386 HEAD

修正:
http://www.jp.freebsd.org/cgi/cvsweb.cgi/src/sys/i386/conf/NOTES.diff?r1=1.1169&r2=1.1170

# CPU_DISABLE_CMPXCHG disables the CMPXCHG instruction on > i386 IA32
# machines.  VmWare 3.x seems to emulate this instruction poorly, causing
# the guest OS to run very slowly.  This problem appears to be fixed in
# VmWare 4.x, at least in version 4.5.2, so that enabling this option with
# VmWare 4.x will result in locking operations to be 20-30 times slower.
# Enabling this with an SMP kernel will cause the kernel to be unusable.

commit log:
My recent measurement shows that CPU_DISABLE_CMPXCHG is no longer necessary with VmWare 4.x. At least with VmWare version 4.5.2, i386 version of atomic_cmpset_int() is about 30 times slower than non-i386 version. It makes this delta a good 5.3 MFC candidate, since otherwise it will mislead users who run FreeBSD under modern VmWare otherwise.
$FreeBSD: src/sys/i386/conf/NOTES,v 1.1170 2004/08/23 15:55:03 sobomax Exp $
$FreeBSD: src/sys/i386/conf/NOTES,v 1.1168.2.1 2004/08/29 11:23:59 sobomax Exp $