machdep.cpu_idle_hlt on a Dual AMD 2000+ MP

[Petri Helenius]

>I've change it to 1 on my dual machine, and so far it appears stable. I have
>noticed that the CPU tempratures appear to be lower now, possibly a
>coincidence as the servers load may have been changing. Should I expect it to
>be lower?

Yes, because instead of running full steam in busyloop, you´re stopping the CPU.

>Also should I expect to see any performance loss, or instability? Does anyone
>know the original reason for setting the defaults this way?

If a process wakes up there might be a scheduling latency up to one HZ tick if you
have HLT enabled on SMP. This is documented at least on the comments on the
source.

Pete