MCHBAR PL1 is not set correctly by Throttled under Debian Bullseye on Lenovo Thinkpad L14 Gen 2

[fangfufu]

I am using Debian Bullseye on a Lenovo Thinkpad L14 Gen 2. Throttled is not changing the MCHBAR PL1 settings. This can be confirmed via sysfs:

root@smithsonian:/home/fangfufu# cat /sys/devices/virtual/powercap/intel-rapl-mmio/intel-rapl-mmio:0/constraint_0_power_limit_uw
20000000

I have set it to 60W in /etc/throttled.conf.

I can increase the limit by running the following in the background:

watch -n 1 'echo 60000000 > /sys/devices/virtual/powercap/intel-rapl-mmio/intel-rapl-mmio:0/constraint_0_power_limit_uw'

It would be nice if throttled does this in the background for me.

I am running Debian Bullseye using the kernel from the backport:

fangfufu@smithsonian:~$ uname -a
Linux smithsonian 5.14.0-0.bpo.2-amd64 #1 SMP Debian 5.14.9-2~bpo11+1 (2021-10-10) x86_64 GNU/Linux

I can confirm that throttled is working correctly:

fangfufu@smithsonian:~$ sudo systemctl status throttled
[sudo] password for fangfufu:
● throttled.service - Stop Intel throttling
     Loaded: loaded (/etc/systemd/system/throttled.service; enabled; vendor preset: enabled)
     Active: active (running) since Sun 2022-01-16 02:10:10 GMT; 33min ago
   Main PID: 115699 (python3)
      Tasks: 2 (limit: 76701)
     Memory: 11.7M
        CPU: 441ms
     CGroup: /system.slice/throttled.service
             └─115699 /opt/throttled/venv/bin/python3 /opt/throttled/throttled.py

Jan 16 02:10:10 smithsonian systemd[1]: Started Stop Intel throttling.
Jan 16 02:10:10 smithsonian python3[115699]: [I] Detected CPU architecture: Intel TigerLake
Jan 16 02:10:10 smithsonian python3[115699]: [I] Trying to unlock MSR allow_writes.
Jan 16 02:10:10 smithsonian python3[115699]: [I] Testing if undervolt is supported...
Jan 16 02:10:10 smithsonian python3[115699]: [I] Testing if HWP is supported...
Jan 16 02:10:10 smithsonian python3[115699]: [I] Loading config file.
Jan 16 02:10:10 smithsonian python3[115699]: [I] Starting main loop.

I set the power properly at /etc/throttled.conf

[GENERAL]
# Enable or disable the script execution
Enabled: True
# SYSFS path for checking if the system is running on AC power
Sysfs_Power_Path: /sys/class/power_supply/AC*/online
# Auto reload config on changes
Autoreload: True

## Settings to apply while connected to Battery power
[BATTERY]
# Update the registers every this many seconds
Update_Rate_s: 30
# Max package power for time window #1
PL1_Tdp_W: 60
# Time window #1 duration
PL1_Duration_s: 28
# Max package power for time window #2
PL2_Tdp_W: 60
# Time window #2 duration
PL2_Duration_S: 0.002
# Max allowed temperature before throttling
Trip_Temp_C: 85
# Set cTDP to normal=0, down=1 or up=2 (EXPERIMENTAL)
cTDP: 0
# Disable BDPROCHOT (EXPERIMENTAL)
Disable_BDPROCHOT: False

## Settings to apply while connected to AC power
[AC]
# Update the registers every this many seconds
Update_Rate_s: 5
# Max package power for time window #1
PL1_Tdp_W: 60
# Time window #1 duration
PL1_Duration_s: 28
# Max package power for time window #2
PL2_Tdp_W: 60
# Time window #2 duration
PL2_Duration_S: 0.002
# Max allowed temperature before throttling
Trip_Temp_C: 95
# Set HWP energy performance hints to 'performance' on high load (EXPERIMENTAL)
# Uncomment only if you really want to use it
# HWP_Mode: False
# Set cTDP to normal=0, down=1 or up=2 (EXPERIMENTAL)
cTDP: 2
# Disable BDPROCHOT (EXPERIMENTAL)
Disable_BDPROCHOT: False

[cor3000]

Possibly already mentioned earlier somewhere else (maybe it's helpful here in this thread):

My workaround is to press the keyboard shortcut FN+h once after each restart.
Even though not (well?) documented for L14 Gen2, this activates the high performance CPU profile and prevents the CPU throttling under load - until the next restart, though.
I've been doing this for the past year as soon as I notice the unwanted CPU throttling kicks in under load.
Still the CPU scales down when idle, as expected.

So far I haven't noticed any negative side effects.

With shortcuts FN+m, FN+l one can switch back to medium or low profile if needed.

[fangfufu]

@cor3000 , where did you find out about this information? FN+m doesn't seem to do anything for me, but FN+h and FN+l both do.

[fangfufu]

I am confirming that this is fixed via #310

[cor3000]

@cor3000 , where did you find out about this information? FN+m doesn't seem to do anything for me, but FN+h and FN+l both do.

I don't remember how I eventually put the clues together... however that's what I found in the Lenovo User Manual for L14 Gen2

Intelligent cooling
The Intelligent Cooling feature helps you adjust fan speed, computer temperature and performance. This feature works in auto mode by default. Press Fn+T to switch between manual mode and auto mode.

https://download.lenovo.com/pccbbs/pubs/l14_gen2_l15_gen2/html_en/index.html#t=en%2FIntelligent_cooling_(topic)_T0000783576.html&rhsearch=FN&rhhlterm=FN&rhsyns=%20

However this FN+t shortcut didn't have any (noticeable) effect on my side.

Then I came across the other shortcuts (FN+h/m/l) documented for other Thinkpad Models, and just "gave it a try"

Maybe from here: https://wiki.archlinux.org/title/Lenovo_ThinkPad_X1_Carbon_(Gen_10)#Performance_modes (even though the model doesn't match, the shortcuts seem to work, maybe not the FN+m (as you noticed), which I don't use anyway)

IIRC: I also saw this in one of the Thinkpad user Guides for an older Model, but as of today I can't find it anymore.

Then I also found this mentioning the FN+H shortcut in case the "Lap Detection" prevents high heat
(I actually have a tilted notebook notebook holder on my desk, it would be really stupid if it's just that)

If I knew how to trigger these FN shortcuts from command line, that would give me a chance to automate these during startup.
Maybe that could even give a simpler fix for the underlying problem than polling/updating a configuration file in an endless loop.

[cor3000]

also this gives the same hint: FN+H (something about a "Lap Detection System")
https://www.reddit.com/r/thinkpad/comments/i4x8i8/tip_for_x1c7_and_perhaps_other_recent_models/

Someone even wrote a patch to disable Lap Detection in the kernel:
https://github.com/JosiahBull/thinkpad_acpi

also mentioned here: https://gist.github.com/sylvainfaivre/512fe8c171582caca3cabaed023188b4#keyboard-shortcut-to-switch-to-performance-mode