[Mesa-users] Technical issue: calculations going incredibly slow

[Jon Brase]

On 5/4/21 4:31 AM, Amedeo Romagnolo via Mesa-users wrote:
>
> This is indeed a good hint. I mean, I don't know which thermal zones 
> represent, but some are indeed > 85 °C. And considering I have a HP 
> Omen, which is famous for overheating, this is surely something I need 
> to consider. What makes me wonder is how it is possible that only MESA 
> is slowed by the CPU overheating and not all the other processes. Is 
> it something possible?

Mesa is unusually CPU-bottlenecked. Most programs tend to bottleneck on 
something other than CPU: For games it's generally graphics, for most 
programs it's user input (that is, each keystroke or click of the mouse 
gives them work to do, but they get it done really quickly and then head 
back to the break room to wait for you to give them more work and gripe 
to all their friends about how humans are so incredibly slow). So even 
if the CPU throttles due to thermal load, the processes that aren't MESA 
may still be able to get enough CPU time that you don't notice them lagging.

MESA, meanwhile, gives the CPU a ton of work to do, and if your computer 
isn't well enough ventilated for the power draw of the CPU, you may very 
well get thermal throttling. That's where a full-sized desktop can come 
in handy: you can  fit all the computing power a single person could 
reasonably need into a laptop these days, at least for work that comes 
in short bursts, but laptops are harder to ventilate and can have 
endurance issues because of that.

A thermal zone is basically just a temperature sensor somewhere inside 
your computer. What exactly each zone covers is going to vary according 
to your hardware, but fairly typically you might see one sensor for the 
whole CPU die, one for each core, one for the graphics card, and maybe 
one for each disk.

Jon Brase