[Speed] intel_pstate C0 bug on isolated CPUs with the performance governor

[Victor Stinner]

I wrote a long article explaing how I identified the bug by testing
Turbo Boost, CPU temperature, CPU frequency, etc.
https://haypo.github.io/intel-cpus-part2.html

Copy/paste of my conclusion:

To get stable benchmarks, the safest fix for all these issues is
probably to set the CPU frequency of the CPUs used by benchmarks to
the minimum. It seems like nothing can reduce the frequency of a CPU
below its minimum.

When running benchmarks, raw timings and CPU performance don't matter.
Only comparisons between benchmark results and stable performances
matter.

Victor