I recently bought a new laptop (Asus Zenbook 14 UX435EG) equipped with the Intel Tiger Lake processor. Unfortunately, I have a problem with the CPU frequency scaling which only appears on Linux (Windows 10 Pro is just fine).
The moment I stress the CPU fully, the system sets the frequency of all cores to 400MHz. This happens a few seconds after the CPU is fully utilised, and I am 100% sure it is not a temperature problem because the cores are bellow 65C.
If I utilise fewer cores, the frequency reduction is not that severe. I understand that I should expect some frequency reduction when the CPU is at full load, but what is happening here is not normal. The CPU temperature is low and the 2.8GHz => 0.4GHz transition happens after 2-3 seconds. To me this seems like a bug. And if that wasn't enough, it appears that the system does not respect the minimum frequency set by cpupower when the CPU is under load.
I am using Debian sid (kernel 5.10), intel_pstate driver, and the "performance" governor. Ubuntu 20.10 ( kernel 5.8 ) and has the same problem. Interestingly, this problem is not present on Intel's Clear Linux (kernel 5.9).
To bring the CPU under load I just run the following 10-30 times:
Code: Select all
python3 -c "while True: pass" &
- Any idea what is causing this?
- How can I completely disable any kind of CPU frequency scaling? I tried to disable intel_pstate driver and use the userspace governor but the problem is still there.
- Any pointers on how to replicate the frequency scaling configuration of Intel's Clear Linux on Debian?
Thank you for your time.