Background Information:
I'm running Ubuntu 24.04.1 LTS (Noble Numbat, kernel 6.8.0-51-generic) on an AMD Ryzen 9 7950X3D, and I'm investigating some odd behavior where the CPU governor/driver will lower the CPU frequency when under full load.
Using the performance governor and the amd-pstate driver, here's what I'm seeing:
| Load | 15 min Load Avg | CPU Temp | CPU Frequency | |
|---|---|---|---|---|
| Idle | 1.12 | 40.8 C | 5,759,000,000 Hz | 5.76 GHz |
| Full | 33.02 | 58.5 C | 4,827,047,000 Hz | 4.83 GHz |
I'm fairly confident that 58.5C isn't hot enough to cause thermal throttling on the CPU, but I'd like to be sure so that I know how to direct my investigation:
- If it's thermal throttling, I'll get a better cooling system.
- If it's not thermal throttling, I'll keep looking into configuration options
This post suggests that I should be able to see throttling information in /sys/devices/system/cpu/cpu*/thermal_throttle/, however the thermal_throttle directory is missing:
/sys/devices/system/cpu/cpu0 $ file *
acpi_cppc: directory
cache: directory
cpufreq: symbolic link to ../cpufreq/policy0
cpuidle: directory
crash_notes: regular file, no read permission
crash_notes_size: regular file, no read permission
driver: symbolic link to ../../../../bus/cpu/drivers/processor
firmware_node: symbolic link to ../../../LNXSYSTM:00/LNXSYBUS:00/ACPI0010:00/ACPI0007:00
hotplug: directory
microcode: directory
node0: symbolic link to ../../node/node0
power: directory
subsystem: symbolic link to ../../../../bus/cpu
topology: directory
uevent: ASCII text, with very long lines (1212)
The Question:
Why is this missing from sysfssysfs, and how can I get the CPU throttling information?
Thanks
