Arch Linux

zoui

Member

Registered: 2020-09-23

Posts: 5

Intel turbo disabled after a few minutes

Hi there !

First of all some information about my CPU :
- i7-9750h, 2.6GHz (4.5Ghz with turbo)
- intel_pstate driver

When I boot up my computer, everything is fine and my CPU can use its turbo functionality, which is reported as enabled by i7z. However after a few minutes I noticed that the freqs are limited to the base max frequency and according to i7z turbo mode is then disabled.

If at this point I try to manually enable turbo via

# echo 0 > /sys/devices/system/cpu/intel\_pstate/no\_turbo

(as root) it doesn't work and I get this error :

Operation not permitted

The problem is that I have no clue of where to look out the find a potential culprit for this. dmesg and journalctl contain no mention of "turbo". I monitored the logs with

journalctl -xe -f

while polling

/sys/devices/system/cpu/intel\_pstate/no\_turbo

and when the latter turns to 1, no entry is added to the logs.

I have disabled tlp to check if it was interfering with something. No luck.

Anyone has any idea ?

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,671

Re: Intel turbo disabled after a few minutes

What laptop model? Sometimes the laptops firmware interferes here and enforces a certain mode based on weird internal heuristics, try and check for a BIOS/UEFI update.

zoui

Member

Registered: 2020-09-23

Posts: 5

Re: Intel turbo disabled after a few minutes

What laptop model? Sometimes the laptops firmware interferes here and enforces a certain mode based on weird internal heuristics, try and check for a BIOS/UEFI update.

It's a Lenovo Y540. I just updated the UEFI but the problem is still present. It does not happen on Windows so I don't think it's UEFI-related. I don't think it happens on other distros I have as well but I will check again.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,671

Re: Intel turbo disabled after a few minutes

Lenovos definitely can be affected by this.

https://www.archlinux.org/packages/comm … throttled/
https://github.com/erpalma/throttled

zoui

Member

Registered: 2020-09-23

Posts: 5

Re: Intel turbo disabled after a few minutes

Lenovos definitely can be affected by this.

https://www.archlinux.org/packages/comm … throttled/
https://github.com/erpalma/throttled

I installed and enabled it, still no luck. The CPU runs cool (45°C at most during the testing, I'm not stressing it) so I don't think the bug comes from a throttling mechanism.

zoui

Member

Registered: 2020-09-23

Posts: 5

Re: Intel turbo disabled after a few minutes

Hi there !

After two weeks I just understood what happens : the turbo is enabled only when the fans are spinning. So in the end V1del you were right, it's probably some BIOS feature. But I find it pretty cool now that I know what it is about, it helps the CPU running cool and keeps the fans off.

Last edited by zoui (2020-10-08 10:36:51)