FS#67616 - [linux] CPU clocks go to base under load

Attached to Project: Arch Linux
Opened by Samega 7Cattac (Samega 7Cattac) - Monday, 17 August 2020, 12:21 GMT
Last edited by freswa (frederik) - Monday, 31 August 2020, 07:56 GMT
Task Type Bug Report
Category Kernel
Status Closed
Assigned To Tobias Powalowski (tpowa)
Jan Alexander Steffens (heftig)
Levente Polyak (anthraxx)
Architecture x86_64
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

I have been noticing that when I use a recent version (at least 5.8.1.arch1-1) my CPU clocks goes to ~800Mhz under load.
The temps don't even hit 70ºC and I can hear the fans turning a bit down.
If I close the software that could be using a lot of CPU it takes like 15secs to go back to normal.
It doesn't happen on LTS version (5.4.58-1-lts).
   cpuinfo.txt (5.3 KiB)
This task depends upon

Closed by  freswa (frederik)
Monday, 31 August 2020, 07:56 GMT
Reason for closing:  Not a bug
Additional comments about closing:  Caused by user space tool
Comment by Samega 7Cattac (Samega 7Cattac) - Tuesday, 18 August 2020, 22:29 GMT
  • Field changed: Percent Complete (100% → 0%)
I'm pretty sure it is.
Found that something is changing my governor from performance to powersave when it gets under load, which doesn't happen on LTS kernel.
Asked someone with a 6700k and the same happened.
Comment by Samega 7Cattac (Samega 7Cattac) - Thursday, 20 August 2020, 17:30 GMT
I posted more details in here: https://bbs.archlinux.org/viewtopic.php?id=258278
Comment by Jan Alexander Steffens (heftig) - Thursday, 20 August 2020, 20:58 GMT
I suspect the actual issue is that some software in your setup is making these changes. And since Linux 5.8, the intel cpufreq driver actually allows software to control the frequency for your CPU.
Comment by Samega 7Cattac (Samega 7Cattac) - Thursday, 20 August 2020, 21:10 GMT
Is there any way to know which software is doing it?

#off-topic: There's nothing on ArchWiki about intel_cpufreq driver
Comment by Torus (T0t0) - Saturday, 29 August 2020, 04:26 GMT
You may have had the same problem I had. That is to say the CPU which remains blocked at the minimum. It took me some time to identify it.
I'm on a laptop with TLP, thanks to its configuration file, I modified the governors from powersave to schedutil.
The problem of slowness has been solved.

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