Notable upstream bugs with related issues

alegidly patched: https://bugzilla.kernel.org/show_bug.cgi?id=115771
maybe not patched yet: https://bugzilla.kernel.org/show_bug.cgi?id=93521

Workaround (to help other who find this bug)

Add `intel_pstate=disable` to `GRUB_CMDLINE_LINUX_DEFAULT` in
/etc/default/grub and update-grub. This will revert to the acpi-cpufreq
driver and ondemand (default) policy.

check with `cpupower frequency-info`

I've observed more sane scaling of CPU frequencies, and better fan speed
and temperature on Haswell. E.g. acpi-cpufreq vs pstate (while
relatively idle)

* temp: ~52 vs 70 degrees
* fan: ~3800 rpm  vs 4600 rpm

pstate will very often turbo boost many cores and seldom drop below
standard max frequency even when lightly loaded per core. When loaded,
temp would bounce up to 89 degrees quickly. I suspect the CPU kept
needing to throttle back often.


** Bug watch added: Linux Kernel Bug Tracker #115771
   http://bugzilla.kernel.org/show_bug.cgi?id=115771

** Bug watch added: Linux Kernel Bug Tracker #93521
   http://bugzilla.kernel.org/show_bug.cgi?id=93521

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https://bugs.launchpad.net/bugs/1598394

Title:
  intel_pstate has too aggressive frequency selection

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