> > The callout code under BSD has always been, uh, 
> > less than optimal.  Since it is O(n) on operations
> > it really sucks on slow processors (VAX, i386, etc.)
> 
> I'm pretty sure FreeBSD has solved this quite some time ago, don't know if
> they used the stuff referenced here. Maybe we should take a look there
> first...
> 
Yes, FreeBSD uses Varghese's callout stuff since loong time ago. 
Probably simplest to get it from there.

-- Ragge