[coreboot] CPU Turbo [KGPE-D16]

Timothy Pearson tpearson at raptorengineering.com
Fri Dec 9 15:51:13 CET 2016

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On 12/08/2016 11:20 PM, Taiidan at gmx.com wrote:
> I am wondering as to:
> * Why 6274 cpu refuses to turbo to the second turbo state with half of
> the cores in use (it stops around 100mhz before the first turbo state)

The CPU will not turbo to the highest frequency unless half the cores
are in the CC6 power state.  Have you verified that the CC6 power saving
mode is enabled via nvramtool?

> * Is it possible to force enable second turbo state for all cpu cores,
> assuming adequate cooling? Or is it controlled on the CPU itself?

This is controlled by a black box on the CPU die itself.  There is no
way to override the settings of this black box unless you have an
engineering sample (obtaining one at this point is illegal in at least
the United States).  We do have some experience overclocking the Opteron
systems through other methods, but won't discuss further outside of a
development contract.

> Off topic but would rather not make another thread:
> * Does NUMA ram alignment matter performance wise with only one physical
> CPU? (RAM being split half and half per core set at the moment)

Yes!  The G34 CPUs are actually two dies in one package, with 4 sticks
of RAM attached to each node (making 8 sticks per package for the KGPE-D16).

> * Does anyone know where I could get a reasonably priced 6287SE or
> 6284SE? or (even better) an engineering model of 62xx?

Those are rare chips and very expensive.  See above for engineering
samples; they're not legal here so I would have no idea.

I hope this helps!

- -- 
Timothy Pearson
Raptor Engineering
+1 (415) 727-8645 (direct line)
+1 (512) 690-0200 (switchboard)
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