One-shot-oriented event timers management

[Alexander Motin]

Brandon Gooch wrote:
> This latest patch causes an interrupt storm with the HPET timer on my
> system. The machine took about 8 minutes to boot and bring me to a
> login prompt. System interactivity (i.e. input from keyboard, output
> on console) was fine, but after checking the output of `systat vmstat
> -1`, I saw the interrupt rate on each HPET entry was over 120k!
> 
> Can I provide any useful detail? Of course, test patches are always welcome :)

I was able to reproduce alike storm in some situations.

Try new version: http://people.freebsd.org/~mav/timers_oneshot7.patch

-- 
Alexander Motin