Re: CONFIG_NO_HZ: missed ticks, stall (keyb IRQ required) [2.6.18-rc4-mm1]

From: Ingo Molnar
Date: Tue Nov 07 2006 - 03:08:46 EST



* Len Brown <len.brown@xxxxxxxxx> wrote:

> So given that C3 on every known system that has shipped to date breaks
> the LAPIC timer (and apparently this applies to C2 on these AMD
> boxes), dynticks needs a solid story for co-existing with C3.

check out 2.6.19-rc4-mm2: it detects this breakage and works it around
by using the PIT as a clock-events source. That did the trick on my
laptop which has this problem too. I agree with you that degrading the
powersaving mode is not an option.

we've got a question about HPET: it seems all recent hardware has it,
but the BIOS rarely mentions it, so the Linux driver does not enable
HPET. Is there any chance to enable HPET (in the chipset?) - this would
probably be a higher-quality clock-events source than the PIT.

Ingo
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