acpi_cpu_idle panic (Was: Re: kernel panic with todays source)

Nate Lawson nate at
Tue Nov 18 22:40:38 PST 2003

On Tue, 18 Nov 2003, Eric Anderson wrote:
> Nate Lawson wrote:
> >cvsup to -current as of today would be a good first start.  The code was
> >committed Nov 15.  Then boot with acpi enabled and post the output of
> >sysctl hw.acpi.cpu.  You can try different levels by doing sysctl
> >hw.acpi.cpu.cx_lowest=x where x is 0...(number_supported_states - 1)
> >
> Thanks! I've rebuilt and am happy to say that nothing is hosed and I
> booted successfully :)
> Here's my sysctl output:
> $ sysctl hw.acpi.cpu
> hw.acpi.cpu.max_speed: 8
> hw.acpi.cpu.current_speed: 4
> hw.acpi.cpu.performance_speed: 8
> hw.acpi.cpu.economy_speed: 4

You should run a benchmark with different values for
hw.acpi.cpu.current_speed to be sure the throttling control still works
ok.  I left it mostly intact so you shouldn't see any problems but it's
still good to test.  As you change it, you should see dmesg output of
"acpi_cpu0: set speed to xx%"

> hw.acpi.cpu.cx_supported: C1/1 C2/1 C3/85 C3/185
> hw.acpi.cpu.cx_lowest: 0
> hw.acpi.cpu.cx_history: 23589/0 0/0 0/0 0/0
> I played with the different levels a bit, and can't tell much difference
> in them. Let me know what else I can try to break with this.  Just for
> the info, I booted with a/c plugged in, but did the sysctl running on
> battery.

You should set hw.acpi.cpu.cx_lowest to 1 regularly and 2 or 3 if you're
using battery.  This will save on heat.  I'd also be interested in if
you'd set it to 3 while on battery and run a typical workload for an hour
and then send me the result of sysctl hw.acpi.cpu.  The cx_history value
helps me know if my scheduler is accurate.

> Eric Anderson	   Systems Administrator      Centaur Technology

Say hi to Tom Crispin for me.  :)


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