Interrupt lockout

[Johnny Billquist <bqt%softjar.se@localhost>]

I've been doing more stuff, and added event counters for missed clock 
interrupts (the hardware can tell if a clock interrupt have been missed).

And funnily enough, I am seeing missed clock interrupts.
And it is not that they are happening while the processor is executing 
the clock interrupt itself. (I have a counter both at entry and exit, 
and the exit counter finds nothing.)

So something seems to be able to lock out the clock from interrupting 
for rather long times. Clock interrupts happens at IPL_SCHED, so this 
would seem to mean that the system is running at IPL_HIGH for extended 
periods (I don't think anything is using the IPL levels in between).

Anyone have any ideas what this might be?

        Johnny