problem in changing from active to passive mode

[Julia Lawall <julia.lawall@inria.fr>]

Hello,

I have an Intel 6130 and an Intel 5218.  These machines have HWP.  They
are configured to boot with active mode and performance as the power
governor.  Since the following commit:

commit a365ab6b9dfbaf8fb4fb4cd5d8a4c55dc4fb8b1c (HEAD, refs/bisect/bad)
Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Date:   Mon Dec 14 21:09:26 2020 +0100

    cpufreq: intel_pstate: Implement the ->adjust_perf() callback

If I change te mode from active to passive, I have the impression that the
machine is no longer able to raise the core frequencies above the minimum.
Changing the mode back to active has no effect.  This persists if I reboot
to another kernel.

Here are some runs that illustrate the problem.  I have tested the
benchmark many times, and apart from this issue its performance is stable.

Intel 6130:

root@yeti-2:/tmp# java -jar dacapo-9.12-MR1-bach.jar avrora -n 3
===== DaCapo 9.12-MR1 avrora starting warmup 1 =====
===== DaCapo 9.12-MR1 avrora completed warmup 1 in 3420 msec =====
===== DaCapo 9.12-MR1 avrora starting warmup 2 =====
===== DaCapo 9.12-MR1 avrora completed warmup 2 in 2536 msec =====
===== DaCapo 9.12-MR1 avrora starting =====
===== DaCapo 9.12-MR1 avrora PASSED in 2502 msec =====
root@yeti-2:/tmp# echo passive | tee /sys/devices/system/cpu/intel_pstate/status
passive
root@yeti-2:/tmp#
root@yeti-2:/tmp# echo active | tee /sys/devices/system/cpu/intel_pstate/status
active
root@yeti-2:/tmp# java -jar dacapo-9.12-MR1-bach.jar avrora -n 3
===== DaCapo 9.12-MR1 avrora starting warmup 1 =====
===== DaCapo 9.12-MR1 avrora completed warmup 1 in 7561 msec =====
===== DaCapo 9.12-MR1 avrora starting warmup 2 =====
===== DaCapo 9.12-MR1 avrora completed warmup 2 in 6528 msec =====
===== DaCapo 9.12-MR1 avrora starting =====
===== DaCapo 9.12-MR1 avrora PASSED in 7796 msec =====

-------------------------------------------------------------------------

Intel 5218:

root@troll-2:/tmp# java -jar dacapo-9.12-MR1-bach.jar avrora -n 3
===== DaCapo 9.12-MR1 avrora starting warmup 1 =====
===== DaCapo 9.12-MR1 avrora completed warmup 1 in 2265 msec =====
===== DaCapo 9.12-MR1 avrora starting warmup 2 =====
===== DaCapo 9.12-MR1 avrora completed warmup 2 in 2033 msec =====
===== DaCapo 9.12-MR1 avrora starting =====
===== DaCapo 9.12-MR1 avrora PASSED in 2068 msec =====
root@troll-2:/tmp# echo passive | tee /sys/devices/system/cpu/intel_pstate/status
passive
root@troll-2:/tmp# echo active | tee /sys/devices/system/cpu/intel_pstate/statusactive
root@troll-2:/tmp# java -jar dacapo-9.12-MR1-bach.jar avrora -n 3
===== DaCapo 9.12-MR1 avrora starting warmup 1 =====
===== DaCapo 9.12-MR1 avrora completed warmup 1 in 4363 msec =====
===== DaCapo 9.12-MR1 avrora starting warmup 2 =====
===== DaCapo 9.12-MR1 avrora completed warmup 2 in 4486 msec =====
===== DaCapo 9.12-MR1 avrora starting =====
===== DaCapo 9.12-MR1 avrora PASSED in 3417 msec =====

-------------------------------------------------------------------------

thanks,
julia