On Thu, 14 Jul 2005, Brown, Len wrote: > >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.
That's an APIC bug. When Intel originally released the APIC (some thirteen years ago) they stated it should be used as a source of the timer interrupt instead of the 8254. There is no excuse for changing the behaviour after so many years. So if you are on a broken system, you may want to work around the bug, but it shouldn't impact good systems. Maciej - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
