"Richard B. Johnson" wrote:
>
> On Wed, 3 Jul 2002, Xinwen - Fu wrote:
>
> > Hi, all,
> > I'm curious that if a network card interrupt happens at the same
> > time as the kernel timer expires, what will happen?
> >
> > It's said the kernel timer is guaranteed accurate. But if
> > interrupts are not masked off, the network interrupt also should get
> > response when a kernel timer expires. So I don't know who will preempt
> > who.
> >
> > Thanks for information!
> >
> > Xinwen Fu
>
> The highest priority interrupt will get serviced first. It's the timer.
> Interrupts are serviced in priority-order. Hardware "remembers" which
> ones are pending so none are lost if some driver doesn't do something
> stupid.
That is true as far as it goes, HOWEVER, timers are serviced
by bottom half code which is run at the end of the
interrupt, WITH THE INTERRUPT SYSTEM ON. Therefore, timer
servicing can be interrupted by an interrupt and thus be
delayed.
-- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Real time sched: http://sourceforge.net/projects/rtsched/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Sun Jul 07 2002 - 22:00:12 EST