upreempt_pri

[Lars Heidieker <lars%heidieker.de@localhost>]

Hi,

I would like to change upreempt_pri to default to 0 as this makes 
wakeups where the interrupted cpu schedules a thread on another cpu 
behave like as if it where scheduled on the interrupted cpu.

For the case that  the to be scheduled on cpu is the interrupted one, 
the behavior is like having upreempt_pri set to 0, as rescheduling 
happens on return too usermode while in the cross cpu case this might be 
delayed until the next timer interrupt.

This change makes some sluggishness regarding X to go a way.
(Solaris defaults to 0 here as well, I think the only reason to set it 
higher is on very big SMP machines where throughput is more important 
then latency)

Lars