Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt

Venkatesh Pallipadi
2005-07-15T18:05:25Z

On Fri, Jul 15, 2005 at 06:54:30PM +0100, Maciej W. Rozycki wrote:
> On Fri, 15 Jul 2005, Venkatesh Pallipadi wrote:
>
> > I wouldn't say it is totally impossible. There are ways in which Linux can work
> > without a reliable Local APIC timer. One option being - make one CPU that gets
> > the external timer interrupt multicast an IPI to all the other CPUs that
> > wants to get periodic timer interrupt.
>
> That's like scratching your left ear with your right hand -- broadcasting
> that external timer interrupt in the first place is more straightforward.
> If you want to exclude CPUs from the list of receivers, just use the
> logical destination mode appropriately.
>

Well.. I tried a patch to do the broadcast thing couple of months ago and
failed to convince everyone :(.

Further, it doesn't work well if you want to exclude some CPUs from the list of recievers. Logical destination is simple only for less than 8 CPUs. Beyond that
with clustered or physical configuration it is difficult.

Thanks,
Venki