I have read through the comments but still don't understand a lot of
things:

Please explain why a higher ratio results in a lower speed.

Please explain in detail what the `CpuRatio` UPD actually does. How does
it relate to `BootFrequency`?

Also, it seems to me that the measurements are void, because the currently
simplified tsc_freq_mhz() implementation doesn't support "flex ratio". I
think we should implement tsc_freq_mhz() correctly first, before jumping
to any conclusions.

Additionally, for the interested reader: flex ratio adapts the maximum
non-turbo ratio. And is mainly a feature to influence the TSC rate...

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2 comments:

• File src/soc/intel/cannonlake/romstage/fsp_params.c:

  • Patch Set #2, Line 79: flex_ratio = rdmsr(MSR_FLEX_RATIO);

    If I understand the EDS correctly, this register's contents survive a reset.
    So the code here doesn't make much sense. It might read a stale value from
    a previous boot instead.

  • Patch Set #2, Line 80: if (CONFIG(OVERRIDE_CPU_FLEX_RATIO))

    > > > > we could do that for sure but trying to leverage more from existing setting without writing […]

    Can you please explain why it is faster with a lower clock speed?

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