[Bug 217809] New: Core frequencies do not float correctly on AMD Ryzen 7 5700U when running on battery

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=217809

            Bug ID: 217809
           Summary: Core frequencies do not float correctly on AMD Ryzen 7
                    5700U when running on battery
           Product: Power Management
           Version: 2.5
          Hardware: AMD
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: cpufreq
          Assignee: linux-pm@vger.kernel.org
          Reporter: soren@stoutner.com
        Regression: No

On my laptop running an AMD Ryzen 7 5700U CPU, when on battery there are
problems with the core frequency logic.  When a process consumes 100% CPU usage
on a single core, the system forces the core frequency to the lowest value (399
MHz) instead of letting it float up to the highest frequency (4.3 GHz).  At the
same time, other cores that have minimal CPU utilization will increase
frequency up to the maximum, meaning that the CPU isn't locked to the lower
frequency as a whole, but that something about
the frequency control logic isn't making the correct decisions.  This causes
the system to run very slowly when on battery.

When the laptop is plugged in the behavior disappears, with cores that are
consuming significant CPU able to increase the frequency to the maximum value. 
Often after plugging in the laptop and then unplugging it, the correct behavior
is maintained, although over time it usually reverts to the constrained
behavior.  Also, sometimes this behavior will disappear if the laptop is
suspended and resumed while on battery.  And, very rarely, the system boots up
on battery and behaves correctly.  All of this indicates that there is some
power management logic that is misbehaving in a way that was not anticipated.

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