machdep.cpu_idle_hlt and SMP perf?

[Daniel Eriksson]

I just finished running 6 sets of (make clean + buildworld +
buildkernel), toggling machdep.cpu_idle_hlt between enabled and disabled
each time (3 of each).

Hardware: 2 x Athlon MP 2600+ on a Tyan Tiger 2466 mobo with 768MB
memory
Disks: 4 x 36GB 10k rpm in RAID-5 config on a SmartArray 6302/64
controller (ciss)
Software: RELENG_6 from yesterday

machdep.cpu_idle_hlt=1
45.01
46.12
45.30

machdep.cpu_idle_hlt=0
43.47
43.09
43.29

Looks like machdep.cpu_idle_hlt=0 shaves ~2 min off the build-time on my
server.

/Daniel