re: tar x cpu bound

> The first thing I don't understand is why the top (or the two top) hits 
> are in idle_loop. Is that because the other fives cores are idle?

>               netbsd`0xffffffff8021ff62
>               netbsd`intr_biglock_wrapper+0x16
>               netbsd`Xhandle_ioapic_level5+0x6a
>               netbsd`acpicpu_cstate_idle_enter+0xdb
>               netbsd`acpicpu_cstate_idle+0xdb
>               netbsd`idle_loop+0x111
>               netbsd`lwp_trampoline+0x17
>               287
>
>               netbsd`0xffffffff8022008f
>               netbsd`AcpiHwReadPort+0xc1
>               netbsd`AcpiHwRead+0x11f
>               netbsd`acpitimer_read_fast+0x11
>               netbsd`acpicpu_cstate_idle_enter+0x82
>               netbsd`acpicpu_cstate_idle+0xdb
>               netbsd`idle_loop+0x111
>               netbsd`lwp_trampoline+0x17
>               292

these just mean that in the idle loop, were calling into
the acpi idle code (which is used to use less power), and
dtrace caught them doing something here.  these _should_
be not related.

i don't have a good response for your other questions yet.