system timer interrupt targets for SMP platforms with local timer support

[Mulyadi Santosa]

Hi...

On Wed, May 18, 2011 at 06:56, Christopher Harvey
<chris at basementcode.com> wrote:
> I half agree. The way I see it now, WITHOUT local timers a timer only needs
> to interrupt one core, and an IPI will interrupt the other.

based on my knowledge that registered timer handler (created by kernel
function, not the one that handle PIT for example) are kept as per CPU
list, then I am fairly sure local timer just need to interrupt its
core and IPI is not really needed.

> My question is:
> Does a global timer need to send an interrupt to both cores when local
> timers are enabled or is a a global timer interrupt on one core combined
> with the local timers enough?

my take is: if local timer (i.e by using LAPIC) is enabled and active,
then global timer is practically not needed. After all, I guess they
would be just overlapping...

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
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