Re: 2.6.19-rc4-mm1: noidlehz problems

[Arjan van de Ven]

On Wed, 2006-11-01 at 13:23 +0100, Pavel Machek wrote:
> Hi!
> 
> First, it would be nice if we had someone listed as a maintainer of
> noidlehz stuff...
> 
> Then... I'm getting strange messages from noidlehz each time I
> unplug/replug AC power (perhaps due to interrupt latency?).

there probably is a different story going on.
When you unplug/replug AC power, several bioses change the meaning of
the software C-states in your system.
(there is a mapping between software visible C states and the hardware
C-states)

In some (hardware) C-states, the local apic timer stops (as does the
TSC), while in others it keeps running. If you change from AC to
battery, the bios can change the meaning of a software C-state from one
where local apic timer keeps going to one where it stops. This obviously
upsets the hrtimers/tickless code since that uses local apic timer for
event generation....


-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/