[arch-general] CPU spikes when lid closed

[Iyán Méndez Veiga]

On Friday, 4 December 2020 22:07:59 CET David Rosenstrauch wrote:
> On 12/3/20 4:35 PM, David Rosenstrauch wrote:
> > I've been having an odd problem.
> > 
> > My laptop works like a charm on its own.  However, when it's connected
> > to a USB-C dock and screen, suddenly apps that were working great start
> > eating up lots of CPU.  (Such as Firefox, Thunderbird, and Zoom.)
> > 
> > After a bit of debugging, I realized that the issue isn't even whether
> > I'm connected to the dock, but rather whether the laptop lid is open or
> > closed:  close the lid and all those apps eat up CPU; open the lid and
> > CPU drops and everything is groovy.
> 
> Finally figured out what's going on here:  apparently the laptop is
> somehow capping the CPU speed at 400MHz whenever the lid is closed.
> (When lid is open it goes up to more like 2-3GHz.)

How is the temperature of the CPU with the lid closed? Maybe the ventilation 
is blocked, the temperature rises and that's why the freq is capped?

But if it happens right away... probably this is not the case. Have you search 
on the wiki for your particular laptop? Maybe there it is a known issue and 
there is some workaround?

> Going to check and see if there's something in the BIOS that controls
> this behavior.  But if anyone has any idea if there's any way to disable
> that within Linux, pls lmk.

Maybe this helps

https://wiki.archlinux.org/index.php/
CPU_frequency_scaling#Setting_maximum_and_minimum_frequencies

-- 
Iyán Méndez Veiga | Physicist
GPG: 0x422E3694311E5AC1