Fwd: Re: Problems with amd FX 8 core and freq scaling

[Jung-uk Kim]

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On 2013-11-11 13:16:47 -0500, Nicholas McKenzie wrote:
> But wouldn't this just disable frequency scaling and the whole 
> point of powerd?

No.  acpi_throttle (and p4tcc) controls T-state.  "Frequency scaling"
should be done by changing P-state.

> On Mon, Nov 11, 2013 at 1:46 AM, Stefan Esser <se at freebsd.org> 
> wrote:
>> 
>> Am 10.11.2013 22:46, schrieb Nicholas Stewart McKenzie:
>>> My computer crashes if I enable powerd. I can't get cpu freq 
>>> scaling to work with my cpu:(P.S. I sent this to both drivers 
>>> and amd64 mailing list...
>> 
>> Hi,
>> 
>> you may want to try booting with the following line added to 
>> /boot/loader.conf (or entered at the boot menu prompt after 
>> breaking out of automatic boot):
>> 
>> hint.acpi_throttle.0.disabled="1"
>> 
>> There have been a number of reports of throttling causing 
>> crashes. This setting does not prevent powerd from adjusting
>> your CPU's clock, it just disables some arcane feature which
>> pre-dates the modern power management methods.

I rewrote acpi_throttle.c at some point to fix the problem but never
committed it because nobody was really interested in testing the
patch.  Also, it is really an arcane and archaic feature:

http://software.intel.com/en-us/blogs/2013/10/15/c-states-p-states-where-the-heck-are-those-t-states

Now I think we should disable the feature by default because it is
causing too much hassle for us (attached).  Any objection?

Jung-uk Kim
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