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Date:      Thu, 28 Aug 2008 19:18:45 +0200
From:      cpghost <cpghost@cordula.ws>
To:        John Baldwin <jhb@freebsd.org>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: powerd freezes system on lower cpu speeds
Message-ID:  <20080828171845.GA14315@epia-2.farid-hajji.net>
In-Reply-To: <200808272222.08568.jhb@freebsd.org>
References:  <20080827134020.GA4973@epia-2.farid-hajji.net> <200808272222.08568.jhb@freebsd.org>

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On Wed, Aug 27, 2008 at 10:22:08PM -0400, John Baldwin wrote:
> 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@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. 

Interesting. So it's probably some bug in the BIOS? I've tried a lot
of different settings there, from failsafe to optimized, selectively
turning Cool & Quiet and other options on or off... but to no avail.

I'll still have to test with another OS though to rule out an FBSD bug,
but that's currently not an option on that box... unless I could
find a stand-alone utility to boot and try without an OS. :)

> I just set 
> debug.cpufreq.lowest in /boot/loader.conf.

Good hint! I've set it to 1240 now, and powerd works like a charm
(at least down to 1240 MHz and back up again). It's a good work around
for now.

> John Baldwin

Thanks for the help,
-cpghost.

-- 
Cordula's Web. http://www.cordula.ws/



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