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dasBook

Member

Registered: 2015-10-27

Posts: 12

MacBook Pro 15" 2015, thermald, cpupower, fan control

I just noticed something weird lately. During compilation time my laptop is sluggish when all CPUs should be up and running at max output. Instead, the laptop is dead quiet, the CPU temp is low, the compilation takes forever, even switching between screens (dwm) has a huge lag. I took a look at the CPU freq and is stuck at 800MHz. Absolutely all the time.

I am running kernel 5.0.0 but I think it started happening before this last update I just never bothered to notice it. I started to poke and prod it trying to figure out what is wrong. The laptop had on it thermald and cpupower and mbpfan.service because I followed some bloke's recipe during installation but I did not do any kind of customization except I set the CPU governor to powersave in the cpupower.conf file. Powersave or performance made no difference.

At first I took out mbpfan service but no change. Then I took out thermald, there was no way in hell I would customize that arcane XML config file. Finally, I disabled and uninstalled cpupower and lo and behold my fans come to life. They're spinning furiously when compiling, the CPUs spring up to 100% and go down with temp. Right now the fans are quietly humming while the CPU temp is hovering at around 58C:

$ cat /sys/devices/platform/applesmc.768/fan*output
2881
2668

So, to recap, I have no means to control the cooling that I know of, yet the laptop is doing ok. I suppose it's doing it either through ACPI, but in a zero-configured way, or in the hardware(??). Does anyone have a similar experience? It left me scratching my head. What is going on?

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,650

Re: MacBook Pro 15" 2015, thermald, cpupower, fan control

Yes normally your hardware/EFI sets the relevant threshholds. You are usually not really supposed to mess with those yourself (unless you really want to, and as shown in this case, ensure your laptop stays quiet with the relevant downside that it would also not clock up) and I'd assume that to be doubly true for Macs given their closed nature.