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proton007

Member

Registered: 2020-08-13

Posts: 10

CPU Frequency stuck at maximum turbo

Hello all,
I have a Thinkpad T470 with an Intel Core i7 processor.
For some reason, the cpu frequency scaling doesn't work dynamically. Once I open an application that loads the CPU, it stays at max frequency and doesn't scale back, even if I close the app.

Here's the output of  cpupower frequency-info:

analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency:  Cannot determine or is not supported.
  hardware limits: 400 MHz - 3.50 GHz
  available cpufreq governors: performance powersave
  current policy: frequency should be within 400 MHz and 3.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency: Unable to call hardware
  current CPU frequency: 3.50 GHz (asserted by call to kernel)
  boost state support:
    Supported: yes
    Active: yes

So it's running at full frequency. Now, if I set the governer to powersave:

 
# cpupower frequency-set -g powersave
Setting cpu: 0
Setting cpu: 1
Setting cpu: 2
Setting cpu: 3

And here's the result:

analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency:  Cannot determine or is not supported.
  hardware limits: 400 MHz - 3.50 GHz
  available cpufreq governors: performance powersave
  current policy: frequency should be within 400 MHz and 3.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency: Unable to call hardware
  current CPU frequency: 3.50 GHz (asserted by call to kernel)
  boost state support:
    Supported: yes
    Active: yes

It's still stuck at full speed!!

Now I unplugged the AC adapter, and the fans spin down, and I see the frequency is down to 800MHz:

analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency:  Cannot determine or is not supported.
  hardware limits: 400 MHz - 3.50 GHz
  available cpufreq governors: performance powersave
  current policy: frequency should be within 400 MHz and 3.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency: Unable to call hardware
  current CPU frequency: 800 MHz (asserted by call to kernel)
  boost state support:
    Supported: yes
    Active: yes 

Plug in the adapter again, and the fans spin up, and I see the frequency is back to full:

analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency:  Cannot determine or is not supported.
  hardware limits: 400 MHz - 3.50 GHz
  available cpufreq governors: performance powersave
  current policy: frequency should be within 400 MHz and 3.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency: Unable to call hardware
  current CPU frequency: 3.50 GHz (asserted by call to kernel)
  boost state support:
    Supported: yes
    Active: yes

I just can't understand why the CPU's frequency is not being dynamically controlled? And it's stuck in it's turbo frequency for some reason. I can disable turbo boost by setting echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo but then it just gets stuck at 2.7GHz.

Any hints on what I should try?
Thanks!!

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,231

Re: CPU Frequency stuck at maximum turbo

Known issue with certain lenovo models, see https://github.com/erpalma/throttled though as far as  I know they should have released an updated UEFI/firmware where it can be fixed "officially" but I don't know if this was only for a select few models.

proton007

Member

Registered: 2020-08-13

Posts: 10

Re: CPU Frequency stuck at maximum turbo

Thanks for your reply.
Well, first thing I did was update the BIOS.
I had the mainboard replaced recently, and apparently this replacement board has not been updated. It showed a BIOS version from 2017.
I will monitor the situation in the coming days to see if the BIOS update has made any difference.

proton007

Member

Registered: 2020-08-13

Posts: 10

Re: CPU Frequency stuck at maximum turbo

Okay, so updating the BIOS didn't help.

But, I noticed that the issue starts when the laptop wakes from suspend. Downgrading the kernel to 5.4.17 and trying again. Will report back soon.

proton007

Member

Registered: 2020-08-13

Posts: 10

Re: CPU Frequency stuck at maximum turbo

Found the issue.

It's an ACPI Interrupt that's hogging CPU0:

Every 1.0s: cat /proc/interrupts                                 thinkpad: Tue Sep  1 08:50:04 2020

            CPU0       CPU1       CPU2       CPU3
   0:          6          0          0          0   IO-APIC    2-edge      timer
   1:        589         11          0          0   IO-APIC    1-edge      i8042
   8:          0          0          1          0   IO-APIC    8-edge      rtc0
   9:    6218091        956          0          0   IO-APIC    9-fasteoi   acpi       <----- THIS NUMBER ON CPU0 KEEPS GOING UP!!
  12:      42991          0          0          0   IO-APIC   12-edge      i8042
  14:          0          0          0          0   IO-APIC   14-fasteoi   INT344B:00
  16:          0          0          0          0   IO-APIC   16-fasteoi   idma64.0, i2c_designware
.0, i801_smbus

And, it has something to do with the dock I'm using. On using the AC adapter everything's fine.

Any suggestions?

Last edited by proton007 (2020-09-01 07:01:05)