[Bug 215714] New: A huge unnecessary power consumption with CONFIG_X86_ACPI_CPUFREQ

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=215714

            Bug ID: 215714
           Summary: A huge unnecessary power consumption with
                    CONFIG_X86_ACPI_CPUFREQ
           Product: Power Management
           Version: 2.5
    Kernel Version: 5.17
          Hardware: x86-64
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: high
          Priority: P1
         Component: cpufreq
          Assignee: linux-pm@vger.kernel.org
          Reporter: aros@gmx.com
        Regression: No

So, here's the situation.

I have a Ryzen 5800X CPU.

Whenever I watch a 4K youtube video (VP9 codec, Mozilla Firefox, no GPU
acceleration, decoded and rendered solely by the CPU) with the ACPI_CPUFREQ
driver the power consumption stays around 50-55 Watts while the CPU is
constantly hitting or staying around the maximum turbo frequency (~4.75GHz).

Whenever I disable Turbo Boost (echo 0 >
/sys/devices/system/cpu/cpufreq/boost), the power consumption instantly
deceases to around 39W with no difference in video decoding, i.e. frames are
not dropped, decoding is smooth and steady.

We are talking about a staggering 30% decrease in power consumption just by
disabling Turbo Boost and limiting CPU frequency to 3.8GHz.

I suppose this is not right and should be fixed/addressed.

I'm using the ondemand governor with default settings.

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