CPU throttling bij recente Lenovo ThinkPad-laptops in Linux

Lenovo heeft toegegeven dat er problemen zijn met recente ThinkPad-laptops als hierop Linux geïnstalleerd wordt. De oorzaak is Intels 'dynamic platform and thermal framework' (DPTF), een driver die de prestaties van de processor beheert. Dit werkt echter alleen onder Windows, met als gevolg dat de processor op zijn standaard limiet blijft staan in Linux.

DPTF is specifiek ontworpen om wat extra comfort te bieden aan gebruikers. Als de laptop op tafel staat, wordt de tdp opgekrikt (tot 51 watt) om hogere prestaties mogelijk te maken. Op schoot blijft de processor echter beperkt tot de standaard energielimieten (15 watt), om zo de temperaturen lager te houden.

Onder andere de ThinkPad X1 Carbon Gen7, T480, T490 en P53 maken hier gebruik van en blijven daarmee in deze energiebesparende 'lap mode' hangen in Linux. Lenovo werkt aan een gevonden oplossing, en zal die spoedig via een firmware-update uitrollen. Die oplossing is overigens redelijk simpel: Lenovo emuleert de werking van DPTF op andere besturingssystemen.

Lenovo's integrale statement:

Some newer Lenovo laptop systems when running Linux are showing thermal throttling giving
reduced performance compared to running with Windows

This is related to the closed-source DPTF settings from Intel that are not supported on Linux -
Linux based systems cannot use these settings to determine if the device is “on desk” or “on
lap”. UL specifications require that the temperature must be at a lower setting when a device is
used “on lap”, as a safety precaution. This setting becomes the default when running Linux
leading to earlier thermal throttling and degraded CPU performance.

Lenovo’s firmware team have designed and implemented an improved and smarter firmware
design that is OS agnostic. The new firmware is able to directly monitor the system sensors to
determine how the system is being used and control the temperature appropriately. Extensive
simulation has been performed to ensure the system mimics the behavior seen with Windows
using DPTF.

Q: Is this compatible with thermald?
A: This implementation operates independently of thermald. We don’t foresee any issues
using both this and thermald going forward but thermald will not be needed in the majority
of cases.

Q: How is the firmware going to get updated?
A: We will be releasing the firmware updates via LVFS. Manual updates for Linux will be
available and automatic updates for Windows (via think vantage). Future laptops will have
this new design preinstalled.
Firmware for the X1 Carbon G7 will be released very soon

Q: Is Intel aware of this plan?
A: Yes.

Q: Which platforms will this be released for?
A: This will be implemented on all future platforms.
We are releasing this initially on the X1 Carbon Gen7. Other platforms will be updated as
we are able to address them

Bron: Notebookcheck