powerd freezes system on lower cpu speeds

[John Baldwin]

On Wednesday 27 August 2008 09:40:20 am cpghost wrote:
> Hello,
>
> I'm building a new system with an AMD Phenom 9350e Quad-Core:
>
>   FreeBSD phenom.example.net 7.1-PRERELEASE FreeBSD 7.1-PRERELEASE #0:
>   Tue Aug 26 19:49:24 UTC 2008 root at phenom.example.net:/usr/obj/usr/\
>   src/sys/GENERIC  i386
>
> Everything's running smoothly, until I start powerd. As soon as
> that happens, the system freezes hard. Trying powerd in the foreground
> with -v shows that it decreased the frequencies a few times, but then
> hangs the system.
>
> So I've tried this manually:
>
> # sysctl dev.cpu.0.freq_levels
> dev.cpu.0.freq_levels: 1985/-1 1736/-1 1488/-1 1240/-1 992/-1 744/-1
>                        496/-1 248/-1
>
> # sysctl dev.cpu.0.freq
> dev.cpu.0.freq: 1985
>
> powerd freezed the system after reaching 1240 when trying 992. If I set
> the frequency manually down to 1240 with:
>
> # sysctl dev.cpu.0.freq=1240
>
> everything's fine. But as soon as I try setting it further down
> (992, 744, 496 or 248), the system freezes too, just the same
> as with powerd. This is 100% reproducible.
>
> So what's going on here?

Hard to say.  My HP nc6220 laptop gets into a lockup where it spends all its 
time processing ACPI events (I think for some of the thermal monitoring the 
BIOS does) if I drop the CPU speed below 400.  I just set 
debug.cpufreq.lowest in /boot/loader.conf.

-- 
John Baldwin