Bug 215714 - A huge unnecessary power consumption with CONFIG_X86_ACPI_CPUFREQ and ondemand governor - Ryzen 5800X
Summary: A huge unnecessary power consumption with CONFIG_X86_ACPI_CPUFREQ and ondeman...
Status: NEW
Alias: None
Product: Power Management
Classification: Unclassified
Component: cpufreq (show other bugs)
Hardware: x86-64 Linux
: P1 high
Assignee: linux-pm@vger.kernel.org
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2022-03-21 13:07 UTC by Artem S. Tashkinov
Modified: 2023-10-08 18:04 UTC (History)
1 user (show)

See Also:
Kernel Version: 5.17
Subsystem:
Regression: No
Bisected commit-id:


Attachments

Description Artem S. Tashkinov 2022-03-21 13:07:24 UTC
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.
Comment 1 Artem S. Tashkinov 2023-10-08 18:04:09 UTC
This is reproducible for other CPUs as well.

Watching HW accelerated videos in Firefox results in ~40% higher power consumption than necessary to actually play them.

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