Re: hlt when idle?

On 02-May-2002 Terry Lambert wrote:
> I think the confusion is because it's useful for the clock to
> be broadcast for one set of reasons, and it's useful to hit on
> only one processor for global handler processing for another
> set of reasons.

Err, some confusion may be that in current we have two different
types of clock interrupt handlers. :)

For example, for hardclock, we ahve hardclock() and
hardclock_process().

We call hardclock() on only one CPU, and hardclock_process() on
all the others.  hardclock() does system-wide global changes and
then runs the thread-specific hardclock_process().
hardclock_process() does thread-specific things like setting up
SIGVTALRM and SIGPROF.  Currently hardclock_process()
(and even more-so, statclock_process()) use the global
sched_lock, thus broadcast doesn't reduce contention unless
it is a staggered broadcast.

-- 

John Baldwin <[e-mail]>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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