Subject: Re: linux-next: Tree for June 13: IO APIC breakage on HP nx6325

From: "Rafael J. Wysocki" <[email-masked]>
Date: Fri, 20 Jun 2008 14:22:11 +0200

On Friday, 20 of June 2008, Matthew Garrett wrote:
> On Fri, Jun 20, 2008 at 01:53:58PM +0200, Rafael J. Wysocki wrote:
> 
> > What exactly I observe is that in this case:
> > 1) The cooling fan is 100% on, as though the box were overheating, which seems
> >    to indicate some serious confusion of the platform (the mechanism turning
> >    the fan 100% on is supposed to be transparent to software).
> > 2) Everything seems to slow down substantially, at least as soon as X is
> >    started.
> 
> What does ACPI claim the trip points are set to in this case? On the 
> 6125, if IRQ 2 is enabled in the APIC then the DSDT sets all the thermal 
> trip points to 16 degrees C. I suspect this means that enabling IRQ 2 is 
> the wrong thing to do on this chipset.

Ah, indeed, thanks for the hint.  This is the output of

$ cat /proc/acpi/thermal_zone/TZ*/trip_points

in the failing case:

critical (S5):           105 C
passive:                 16 C: tc1=1 tc2=2 tsp=100 devices=C000 C001 
active[0]:               16 C: devices=C34F 
active[1]:               16 C: devices=C350 
active[2]:               16 C: devices=C351 
active[3]:               16 C: devices=C352 
critical (S5):           100 C
passive:                 16 C: tc1=1 tc2=2 tsp=300 devices=C000 C001 
critical (S5):           100 C
passive:                 16 C: tc1=1 tc2=2 tsp=300 devices=C000 C001 

(also available at: http://www.sisk.pl/kernel/debug/20080620/trip-points.txt).

So, the observed slowdown may be a result of throttling.

Thanks,
Rafael