On 02/06/2012 11:31 AM, Matthew Garrett wrote:

On Mon, Feb 06, 2012 at 08:17:11AM -0800, Andi Kleen wrote:

quoted

+#define reduction_pctg(cpu) \
+	per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))

I don't like using percentages here - we end up with the potential for 
several percentages to end up mapping to the same P state.

Does it matter?

I've sent a

patch that replaces the percentage code with just stepping through P 
states instead. But otherwise, yes, this seems sensible. An open 
question is whether we should be doing the same on _PPC notifications. 
There's some vague evidence that Windows does.

If you stepped by P-states, then you behave entirely differently
on a machine with many P-states vs a machine with few P-states.

There is code floating about that exposes every 100 MHz step on SNB
and later as a P-state -- you can have quite a few...

thanks,
-Len Brown, Intel Open Source Technology Center