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

Brown, Len
2005-07-14T21:37:08Z

>Of course using APIC internal timers is generally the best idea on SMP,
>but they may have had reasons to avoid them (it's not an ISA interrupt,
so
>it could have been simply out of question in the initial design).

Best? No.

Local APIC timers are based on a clock which on many processors will
STOP when the processor enters power saving idle states, such as C3.
So the LAPIC timer will not accurately reflect how much time
has passed across entry/exit from idle.

True, this has not been an issue on SMP, since there have not been
SMP systems shipping with C3, but as you know soon everything
interesting will be SMP...

-Len