Re: [Xen-devel] [Xen-users] Xen 4.3.1 / Linux 3.12 panic

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.11.13 at 14:10, Wouter de Geus <benv-xensource.com@xxxxxxxxxxxxx> 
>>> wrote:
> * Jan Beulich <JBeulich@xxxxxxxx> [2013-11-07 11:57:17 +0000]:
> 
>> > - PowerCap     [P-state 0] (P-state 0 through 4)
>> 
>> Now we'd need to know what HPC actually means (it means nothing
>> to me in this context) - I'd have expected the PowerCap (as referring
>> to P-states) to be the interesting one.
> 
> Would you like me to test the PowerCap setting? If so, in combination with
> the other settings set to what? Note that the PowerCap setting can't be
> disabled by itself. (unless P-state 4 counts as disabled?)
> 
> According to a faq on supermicro.com (this is a Supermicro board after all)
> http://www.supermicro.com/Aplus/support/faqs/faq.cfm?faq=13400 
> ---
> Q: I noticed that the newer BIOS supporting AMD 6200 series CPUs have a
>    P-state HPC Mode option. Can you provide some info on this mode?
> A: HPC mode only keeps maximum and minimum states. In system idle mode CPU
>    will stay at P4 state for power saving. Once CPU detects higher
>    activities, CPU will jump up to P0 or boost state to reduce clock ramp
>    up latency.

That suggests that P4 is the lowest power state (and the only low
power one in HPC mode), i.e. not meaning disabled. P0 alone would
then mean disabled afaict. And in non-HPC mode I would conclude
intermediate states are also allowed, in which case limiting the number
of states might be interesting for you to try out.

Jan


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