Bug 215714

Summary: A huge unnecessary power consumption with CONFIG_X86_ACPI_CPUFREQ and ondemand governor - Ryzen 5800X
Product: Power Management Reporter: Artem S. Tashkinov (aros)
Component: cpufreqAssignee: linux-pm (linux-pm)
Status: NEW ---    
Severity: high CC: rui.zhang
Priority: P1    
Hardware: x86-64   
OS: Linux   
Kernel Version: 5.17 Subsystem:
Regression: No Bisected commit-id:

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.