John Baldwin [jhb@FreeBSD.org] wrote :
>
> On 01-May-2002 Jonathan Mini wrote:
> > Andrew Gallatin [gallatin@cs.duke.edu] wrote :
> >> > No, the interrupts seem to be round-robin, but each clock intr is only
> >> > sent to one CPU unlike on alpha where they are broadcast.
> >>
> >> So each CPU gets (1/num_cpu) * hz clock interrupts/sec?
> >
> > Yes, but because the timer is set to num_cpu*hz, each CPU ends up getting
> > the normal hz interrupts. That's why it runs round-robin but looks like a
> > broadcast.
>
> Eh, are you talking about the Alpha? On x86 we don't do this and have to use
> IPI's to simulate a broadcast-type deal.
>
I am obviously thinking about some other SMP implementation, but I have no
idea which one. Somebody, somewhere, sets the routing of the clock interrupt
to be delivered in a round-robin fashion, and then multiplies the clock
frequency by the number of processors. They're really proud of this solution,
because (they claim) it reduces contentions of clock-triggered events across
processors.
Maybe it was Sun?
--
Jonathan Mini <mini@freebsd.org>
http://www.haikugeek.com
"He who is not aware of his ignorance will be only misled by his knowledge."
-- Richard Whatley
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