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    SubjectRe: [PATCH 4/5] ACPI: Do cpufreq clamping for throttling per package v2
    On 02/06/2012 11:31 AM, Matthew Garrett wrote:

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




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